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diff --git a/doc/altos.xsl b/doc/altos.xsl deleted file mode 100644 index 6092dfcb..00000000 --- a/doc/altos.xsl +++ /dev/null @@ -1,1612 +0,0 @@ -<?xml version="1.0" encoding="utf-8" ?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" -"/usr/share/xml/docbook/schema/dtd/4.5/docbookx.dtd"> - -<book> - <title>AltOS</title> - <subtitle>Altos Metrum Operating System</subtitle> - <bookinfo> - <author> - <firstname>Keith</firstname> - <surname>Packard</surname> - </author> - <copyright> - <year>2010</year> - <holder>Keith Packard</holder> - </copyright> - <legalnotice> - <para> - This document is released under the terms of the - <ulink url="http://creativecommons.org/licenses/by-sa/3.0/"> - Creative Commons ShareAlike 3.0 - </ulink> - license. - </para> - </legalnotice> - <revhistory> - <revision> - <revnumber>1.1</revnumber> - <date>05 November 2012</date> - <revremark>Portable version</revremark> - </revision> - <revision> - <revnumber>0.1</revnumber> - <date>22 November 2010</date> - <revremark>Initial content</revremark> - </revision> - </revhistory> - </bookinfo> - <chapter> - <title>Overview</title> - <para> - AltOS is a operating system built for a variety of - microcontrollers used in Altus Metrum devices. It has a simple - porting layer for each CPU while providing a convenient - operating enviroment for the developer. AltOS currently - supports three different CPUs: - <itemizedlist> - <listitem> - <para> - STM32L series from ST Microelectronics. This ARM Cortex-M3 - based microcontroller offers low power consumption and a - wide variety of built-in peripherals. Altus Metrum uses - this in the TeleMega, MegaDongle and TeleLCO projects. - </para> - </listitem> - <listitem> - <para> - CC1111 from Texas Instruments. This device includes a - fabulous 10mW digital RF transceiver along with an - 8051-compatible processor core and a range of - peripherals. This is used in the TeleMetrum, TeleMini, - TeleDongle and TeleFire projects which share the need for - a small microcontroller and an RF interface. - </para> - </listitem> - <listitem> - <para> - ATmega32U4 from Atmel. This 8-bit AVR microcontroller is - one of the many used to create Arduino boards. The 32U4 - includes a USB interface, making it easy to connect to - other computers. Altus Metrum used this in prototypes of - the TeleScience and TelePyro boards; those have been - switched to the STM32L which is more capable and cheaper. - </para> - </listitem> - </itemizedlist> - Among the features of AltOS are: - <itemizedlist> - <listitem> - <para>Multi-tasking. While microcontrollers often don't - provide separate address spaces, it's often easier to write - code that operates in separate threads instead of tying - everything into one giant event loop. - </para> - </listitem> - <listitem> - <para>Non-preemptive. This increases latency for thread - switching but reduces the number of places where context - switching can occur. It also simplifies the operating system - design somewhat. Nothing in the target system (rocket flight - control) has tight timing requirements, and so this seems like - a reasonable compromise. - </para> - </listitem> - <listitem> - <para>Sleep/wakeup scheduling. Taken directly from ancient - Unix designs, these two provide the fundemental scheduling - primitive within AltOS. - </para> - </listitem> - <listitem> - <para>Mutexes. As a locking primitive, mutexes are easier to - use than semaphores, at least in my experience. - </para> - </listitem> - <listitem> - <para>Timers. Tasks can set an alarm which will abort any - pending sleep, allowing operations to time-out instead of - blocking forever. - </para> - </listitem> - </itemizedlist> - </para> - <para> - The device drivers and other subsystems in AltOS are - conventionally enabled by invoking their _init() function from - the 'main' function before that calls - ao_start_scheduler(). These functions initialize the pin - assignments, add various commands to the command processor and - may add tasks to the scheduler to handle the device. A typical - main program, thus, looks like: - <programlisting> - void - main(void) - { - ao_clock_init(); - - /* Turn on the LED until the system is stable */ - ao_led_init(LEDS_AVAILABLE); - ao_led_on(AO_LED_RED); - ao_timer_init(); - ao_cmd_init(); - ao_usb_init(); - ao_monitor_init(AO_LED_GREEN, TRUE); - ao_rssi_init(AO_LED_RED); - ao_radio_init(); - ao_packet_slave_init(); - ao_packet_master_init(); - #if HAS_DBG - ao_dbg_init(); - #endif - ao_config_init(); - ao_start_scheduler(); - } - </programlisting> - As you can see, a long sequence of subsystems are initialized - and then the scheduler is started. - </para> - </chapter> - <chapter> - <title>AltOS Porting Layer</title> - <para> - AltOS provides a CPU-independent interface to various common - microcontroller subsystems, including GPIO pins, interrupts, - SPI, I2C, USB and asynchronous serial interfaces. By making - these CPU-independent, device drivers, generic OS and - application code can all be written that work on any supported - CPU. Many of the architecture abstraction interfaces are - prefixed with ao_arch. - </para> - <section> - <title>Low-level CPU operations</title> - <para> - These primitive operations provide the abstraction needed to - run the multi-tasking framework while providing reliable - interrupt delivery. - </para> - <section> - <title>ao_arch_block_interrupts/ao_arch_release_interrupts</title> - <programlisting> - static inline void - ao_arch_block_interrupts(void); - - static inline void - ao_arch_release_interrupts(void); - </programlisting> - <para> - These disable/enable interrupt delivery, they may not - discard any interrupts. Use these for sections of code that - must be atomic with respect to any code run from an - interrupt handler. - </para> - </section> - <section> - <title>ao_arch_save_regs, ao_arch_save_stack, - ao_arch_restore_stack</title> - <programlisting> - static inline void - ao_arch_save_regs(void); - - static inline void - ao_arch_save_stack(void); - - static inline void - ao_arch_restore_stack(void); - </programlisting> - <para> - These provide all of the support needed to switch between - tasks.. ao_arch_save_regs must save all CPU registers to the - current stack, including the interrupt enable - state. ao_arch_save_stack records the current stack location - in the current ao_task structure. ao_arch_restore_stack - switches back to the saved stack, restores all registers and - branches to the saved return address. - </para> - </section> - <section> - <title>ao_arch_wait_interupt</title> - <programlisting> - #define ao_arch_wait_interrupt() - </programlisting> - <para> - This stops the CPU, leaving clocks and interrupts - enabled. When an interrupt is received, this must wake up - and handle the interrupt. ao_arch_wait_interrupt is entered - with interrupts disabled to ensure that there is no gap - between determining that no task wants to run and idling the - CPU. It must sleep the CPU, process interrupts and then - disable interrupts again. If the CPU doesn't have any - reduced power mode, this must at the least allow pending - interrupts to be processed. - </para> - </section> - </section> - <section> - <title>GPIO operations</title> - <para> - These functions provide an abstract interface to configure and - manipulate GPIO pins. - </para> - <section> - <title>GPIO setup</title> - <para> - These macros may be invoked at system initialization time to - configure pins as needed for system operation. One tricky - aspect is that some chips provide direct access to specific - GPIO pins while others only provide access to a whole - register full of pins. To support this, the GPIO macros - provide both port+bit and pin arguments. Simply define the - arguments needed for the target platform and leave the - others undefined. - </para> - <section> - <title>ao_enable_output</title> - <programlisting> - #define ao_enable_output(port, bit, pin, value) - </programlisting> - <para> - Set the specified port+bit (also called 'pin') for output, - initializing to the specified value. The macro must avoid - driving the pin with the opposite value if at all - possible. - </para> - </section> - <section> - <title>ao_enable_input</title> - <programlisting> - #define ao_enable_input(port, bit, mode) - </programlisting> - <para> - Sets the specified port/bit to be an input pin. 'mode' is - a combination of one or more of the following. Note that - some platforms may not support the desired mode. In that - case, the value will not be defined so that the program - will fail to compile. - <itemizedlist> - <listitem> -<para> - AO_EXTI_MODE_PULL_UP. Apply a pull-up to the pin; a - disconnected pin will read as 1. -</para> - </listitem> - <listitem> -<para> - AO_EXTI_MODE_PULL_DOWN. Apply a pull-down to the pin; - a disconnected pin will read as 0. -</para> - </listitem> - <listitem> -<para> - 0. Don't apply either a pull-up or pull-down. A - disconnected pin will read an undetermined value. -</para> - </listitem> - </itemizedlist> - </para> - </section> - </section> - <section> - <title>Reading and writing GPIO pins</title> - <para> - These macros read and write individual GPIO pins. - </para> - <section> - <title>ao_gpio_set</title> - <programlisting> - #define ao_gpio_set(port, bit, pin, value) - </programlisting> - <para> - Sets the specified port/bit or pin to the indicated value - </para> - </section> - <section> - <title>ao_gpio_get</title> - <programlisting> - #define ao_gpio_get(port, bit, pin) - </programlisting> - <para> - Returns either 1 or 0 depending on whether the input to - the pin is high or low. - </para> - </section> - </section> - </section> - </chapter> - <chapter> - <title>Programming the 8051 with SDCC</title> - <para> - The 8051 is a primitive 8-bit processor, designed in the mists - of time in as few transistors as possible. The architecture is - highly irregular and includes several separate memory - spaces. Furthermore, accessing stack variables is slow, and the - stack itself is of limited size. While SDCC papers over the - instruction set, it is not completely able to hide the memory - architecture from the application designer. - </para> - <para> - When built on other architectures, the various SDCC-specific - symbols are #defined as empty strings so they don't affect the compiler. - </para> - <section> - <title>8051 memory spaces</title> - <para> - The __data/__xdata/__code memory spaces below were completely - separate in the original 8051 design. In the cc1111, this - isn't true—they all live in a single unified 64kB address - space, and so it's possible to convert any address into a - unique 16-bit address. SDCC doesn't know this, and so a - 'global' address to SDCC consumes 3 bytes of memory, 1 byte as - a tag indicating the memory space and 2 bytes of offset within - that space. AltOS avoids these 3-byte addresses as much as - possible; using them involves a function call per byte - access. The result is that nearly every variable declaration - is decorated with a memory space identifier which clutters the - code but makes the resulting code far smaller and more - efficient. - </para> - <section> - <title>__data</title> - <para> - The 8051 can directly address these 128 bytes of - memory. This makes them precious so they should be - reserved for frequently addressed values. Oh, just to - confuse things further, the 8 general registers in the - CPU are actually stored in this memory space. There are - magic instructions to 'bank switch' among 4 banks of - these registers located at 0x00 - 0x1F. AltOS uses only - the first bank at 0x00 - 0x07, leaving the other 24 - bytes available for other data. - </para> - </section> - <section> - <title>__idata</title> - <para> - There are an additional 128 bytes of internal memory - that share the same address space as __data but which - cannot be directly addressed. The stack normally - occupies this space and so AltOS doesn't place any - static storage here. - </para> - </section> - <section> - <title>__xdata</title> - <para> - This is additional general memory accessed through a - single 16-bit address register. The CC1111F32 has 32kB - of memory available here. Most program data should live - in this memory space. - </para> - </section> - <section> - <title>__pdata</title> - <para> - This is an alias for the first 256 bytes of __xdata - memory, but uses a shorter addressing mode with - single global 8-bit value for the high 8 bits of the - address and any of several 8-bit registers for the low 8 - bits. AltOS uses a few bits of this memory, it should - probably use more. - </para> - </section> - <section> - <title>__code</title> - <para> - All executable code must live in this address space, but - you can stick read-only data here too. It is addressed - using the 16-bit address register and special 'code' - access opcodes. Anything read-only should live in this space. - </para> - </section> - <section> - <title>__bit</title> - <para> - The 8051 has 128 bits of bit-addressible memory that - lives in the __data segment from 0x20 through - 0x2f. Special instructions access these bits - in a single atomic operation. This isn't so much a - separate address space as a special addressing mode for - a few bytes in the __data segment. - </para> - </section> - <section> - <title>__sfr, __sfr16, __sfr32, __sbit</title> - <para> - Access to physical registers in the device use this mode - which declares the variable name, its type and the - address it lives at. No memory is allocated for these - variables. - </para> - </section> - </section> - <section> - <title>Function calls on the 8051</title> - <para> - Because stack addressing is expensive, and stack space - limited, the default function call declaration in SDCC - allocates all parameters and local variables in static global - memory. Just like fortran. This makes these functions - non-reentrant, and also consume space for parameters and - locals even when they are not running. The benefit is smaller - code and faster execution. - </para> - <section> - <title>__reentrant functions</title> - <para> - All functions which are re-entrant, either due to recursion - or due to a potential context switch while executing, should - be marked as __reentrant so that their parameters and local - variables get allocated on the stack. This ensures that - these values are not overwritten by another invocation of - the function. - </para> - <para> - Functions which use significant amounts of space for - arguments and/or local variables and which are not often - invoked can also be marked as __reentrant. The resulting - code will be larger, but the savings in memory are - frequently worthwhile. - </para> - </section> - <section> - <title>Non __reentrant functions</title> - <para> - All parameters and locals in non-reentrant functions can - have data space decoration so that they are allocated in - __xdata, __pdata or __data space as desired. This can avoid - consuming __data space for infrequently used variables in - frequently used functions. - </para> - <para> - All library functions called by SDCC, including functions - for multiplying and dividing large data types, are - non-reentrant. Because of this, interrupt handlers must not - invoke any library functions, including the multiply and - divide code. - </para> - </section> - <section> - <title>__interrupt functions</title> - <para> - Interrupt functions are declared with with an __interrupt - decoration that includes the interrupt number. SDCC saves - and restores all of the registers in these functions and - uses the 'reti' instruction at the end so that they operate - as stand-alone interrupt handlers. Interrupt functions may - call the ao_wakeup function to wake AltOS tasks. - </para> - </section> - <section> - <title>__critical functions and statements</title> - <para> - SDCC has built-in support for suspending interrupts during - critical code. Functions marked as __critical will have - interrupts suspended for the whole period of - execution. Individual statements may also be marked as - __critical which blocks interrupts during the execution of - that statement. Keeping critical sections as short as - possible is key to ensuring that interrupts are handled as - quickly as possible. AltOS doesn't use this form in shared - code as other compilers wouldn't know what to do. Use - ao_arch_block_interrupts and ao_arch_release_interrupts instead. - </para> - </section> - </section> - </chapter> - <chapter> - <title>Task functions</title> - <para> - This chapter documents how to create, destroy and schedule AltOS tasks. - </para> - <section> - <title>ao_add_task</title> - <programlisting> - void - ao_add_task(__xdata struct ao_task * task, - void (*start)(void), - __code char *name); - </programlisting> - <para> - This initializes the statically allocated task structure, - assigns a name to it (not used for anything but the task - display), and the start address. It does not switch to the - new task. 'start' must not ever return; there is no place - to return to. - </para> - </section> - <section> - <title>ao_exit</title> - <programlisting> - void - ao_exit(void) - </programlisting> - <para> - This terminates the current task. - </para> - </section> - <section> - <title>ao_sleep</title> - <programlisting> - void - ao_sleep(__xdata void *wchan) - </programlisting> - <para> - This suspends the current task until 'wchan' is signaled - by ao_wakeup, or until the timeout, set by ao_alarm, - fires. If 'wchan' is signaled, ao_sleep returns 0, otherwise - it returns 1. This is the only way to switch to another task. - </para> - <para> - Because ao_wakeup wakes every task waiting on a particular - location, ao_sleep should be used in a loop that first checks - the desired condition, blocks in ao_sleep and then rechecks - until the condition is satisfied. If the location may be - signaled from an interrupt handler, the code will need to - block interrupts around the block of code. Here's a complete - example: - <programlisting> - ao_arch_block_interrupts(); - while (!ao_radio_done) - ao_sleep(&ao_radio_done); - ao_arch_release_interrupts(); - </programlisting> - </para> - </section> - <section> - <title>ao_wakeup</title> - <programlisting> - void - ao_wakeup(__xdata void *wchan) - </programlisting> - <para> - Wake all tasks blocked on 'wchan'. This makes them - available to be run again, but does not actually switch - to another task. Here's an example of using this: - <programlisting> - if (RFIF & RFIF_IM_DONE) { - ao_radio_done = 1; - ao_wakeup(&ao_radio_done); - RFIF &= ~RFIF_IM_DONE; - } - </programlisting> - Note that this need not block interrupts as the ao_sleep block - can only be run from normal mode, and so this sequence can - never be interrupted with execution of the other sequence. - </para> - </section> - <section> - <title>ao_alarm</title> - <programlisting> - void - ao_alarm(uint16_t delay); - - void - ao_clear_alarm(void); - </programlisting> - <para> - Schedules an alarm to fire in at least 'delay' ticks. If the - task is asleep when the alarm fires, it will wakeup and - ao_sleep will return 1. ao_clear_alarm resets any pending - alarm so that it doesn't fire at some arbitrary point in the - future. - <programlisting> - ao_alarm(ao_packet_master_delay); - ao_arch_block_interrupts(); - while (!ao_radio_dma_done) - if (ao_sleep(&ao_radio_dma_done) != 0) - ao_radio_abort(); - ao_arch_release_interrupts(); - ao_clear_alarm(); - </programlisting> - In this example, a timeout is set before waiting for - incoming radio data. If no data is received before the - timeout fires, ao_sleep will return 1 and then this code - will abort the radio receive operation. - </para> - </section> - <section> - <title>ao_start_scheduler</title> - <programlisting> - void - ao_start_scheduler(void); - </programlisting> - <para> - This is called from 'main' when the system is all - initialized and ready to run. It will not return. - </para> - </section> - <section> - <title>ao_clock_init</title> - <programlisting> - void - ao_clock_init(void); - </programlisting> - <para> - This initializes the main CPU clock and switches to it. - </para> - </section> - </chapter> - <chapter> - <title>Timer Functions</title> - <para> - AltOS sets up one of the CPU timers to run at 100Hz and - exposes this tick as the fundemental unit of time. At each - interrupt, AltOS increments the counter, and schedules any tasks - waiting for that time to pass, then fires off the sensors to - collect current data readings. Doing this from the ISR ensures - that the values are sampled at a regular rate, independent - of any scheduling jitter. - </para> - <section> - <title>ao_time</title> - <programlisting> - uint16_t - ao_time(void) - </programlisting> - <para> - Returns the current system tick count. Note that this is - only a 16 bit value, and so it wraps every 655.36 seconds. - </para> - </section> - <section> - <title>ao_delay</title> - <programlisting> - void - ao_delay(uint16_t ticks); - </programlisting> - <para> - Suspend the current task for at least 'ticks' clock units. - </para> - </section> - <section> - <title>ao_timer_set_adc_interval</title> - <programlisting> - void - ao_timer_set_adc_interval(uint8_t interval); - </programlisting> - <para> - This sets the number of ticks between ADC samples. If set - to 0, no ADC samples are generated. AltOS uses this to - slow down the ADC sampling rate to save power. - </para> - </section> - <section> - <title>ao_timer_init</title> - <programlisting> - void - ao_timer_init(void) - </programlisting> - <para> - This turns on the 100Hz tick. It is required for any of the - time-based functions to work. It should be called by 'main' - before ao_start_scheduler. - </para> - </section> - </chapter> - <chapter> - <title>AltOS Mutexes</title> - <para> - AltOS provides mutexes as a basic synchronization primitive. Each - mutexes is simply a byte of memory which holds 0 when the mutex - is free or the task id of the owning task when the mutex is - owned. Mutex calls are checked—attempting to acquire a mutex - already held by the current task or releasing a mutex not held - by the current task will both cause a panic. - </para> - <section> - <title>ao_mutex_get</title> - <programlisting> - void - ao_mutex_get(__xdata uint8_t *mutex); - </programlisting> - <para> - Acquires the specified mutex, blocking if the mutex is - owned by another task. - </para> - </section> - <section> - <title>ao_mutex_put</title> - <programlisting> - void - ao_mutex_put(__xdata uint8_t *mutex); - </programlisting> - <para> - Releases the specified mutex, waking up all tasks waiting - for it. - </para> - </section> - </chapter> - <chapter> - <title>DMA engine</title> - <para> - The CC1111 and STM32L both contain a useful bit of extra - hardware in the form of a number of programmable DMA - engines. They can be configured to copy data in memory, or - between memory and devices (or even between two devices). AltOS - exposes a general interface to this hardware and uses it to - handle both internal and external devices. - </para> - <para> - Because the CC1111 and STM32L DMA engines are different, the - interface to them is also different. As the DMA engines are - currently used to implement platform-specific drivers, this - isn't yet a problem. - </para> - <para> - Code using a DMA engine should allocate one at startup - time. There is no provision to free them, and if you run out, - AltOS will simply panic. - </para> - <para> - During operation, the DMA engine is initialized with the - transfer parameters. Then it is started, at which point it - awaits a suitable event to start copying data. When copying data - from hardware to memory, that trigger event is supplied by the - hardware device. When copying data from memory to hardware, the - transfer is usually initiated by software. - </para> - <section> - <title>CC1111 DMA Engine</title> - <section> - <title>ao_dma_alloc</title> - <programlisting> - uint8_t - ao_dma_alloc(__xdata uint8_t *done) - </programlisting> - <para> - Allocate a DMA engine, returning the identifier. 'done' is - cleared when the DMA is started, and then receives the - AO_DMA_DONE bit on a successful transfer or the - AO_DMA_ABORTED bit if ao_dma_abort was called. Note that it - is possible to get both bits if the transfer was aborted - after it had finished. - </para> - </section> - <section> - <title>ao_dma_set_transfer</title> - <programlisting> - void - ao_dma_set_transfer(uint8_t id, - void __xdata *srcaddr, - void __xdata *dstaddr, - uint16_t count, - uint8_t cfg0, - uint8_t cfg1) - </programlisting> - <para> - Initializes the specified dma engine to copy data - from 'srcaddr' to 'dstaddr' for 'count' units. cfg0 and - cfg1 are values directly out of the CC1111 documentation - and tell the DMA engine what the transfer unit size, - direction and step are. - </para> - </section> - <section> - <title>ao_dma_start</title> - <programlisting> - void - ao_dma_start(uint8_t id); - </programlisting> - <para> - Arm the specified DMA engine and await a signal from - either hardware or software to start transferring data. - </para> - </section> - <section> - <title>ao_dma_trigger</title> - <programlisting> - void - ao_dma_trigger(uint8_t id) - </programlisting> - <para> - Trigger the specified DMA engine to start copying data. - </para> - </section> - <section> - <title>ao_dma_abort</title> - <programlisting> - void - ao_dma_abort(uint8_t id) - </programlisting> - <para> - Terminate any in-progress DMA transaction, marking its - 'done' variable with the AO_DMA_ABORTED bit. - </para> - </section> - </section> - <section> - <title>STM32L DMA Engine</title> - <section> - <title>ao_dma_alloc</title> - <programlisting> - uint8_t ao_dma_done[]; - - void - ao_dma_alloc(uint8_t index); - </programlisting> - <para> - Reserve a DMA engine for exclusive use by one - driver. - </para> - </section> - <section> - <title>ao_dma_set_transfer</title> - <programlisting> - void - ao_dma_set_transfer(uint8_t id, - void *peripheral, - void *memory, - uint16_t count, - uint32_t ccr); - </programlisting> - <para> - Initializes the specified dma engine to copy data between - 'peripheral' and 'memory' for 'count' units. 'ccr' is a - value directly out of the STM32L documentation and tells the - DMA engine what the transfer unit size, direction and step - are. - </para> - </section> - <section> - <title>ao_dma_set_isr</title> - <programlisting> - void - ao_dma_set_isr(uint8_t index, void (*isr)(int)) - </programlisting> - <para> - This sets a function to be called when the DMA transfer - completes in lieu of setting the ao_dma_done bits. Use this - when some work needs to be done when the DMA finishes that - cannot wait until user space resumes. - </para> - </section> - <section> - <title>ao_dma_start</title> - <programlisting> - void - ao_dma_start(uint8_t id); - </programlisting> - <para> - Arm the specified DMA engine and await a signal from either - hardware or software to start transferring data. - 'ao_dma_done[index]' is cleared when the DMA is started, and - then receives the AO_DMA_DONE bit on a successful transfer - or the AO_DMA_ABORTED bit if ao_dma_abort was called. Note - that it is possible to get both bits if the transfer was - aborted after it had finished. - </para> - </section> - <section> - <title>ao_dma_done_transfer</title> - <programlisting> - void - ao_dma_done_transfer(uint8_t id); - </programlisting> - <para> - Signals that a specific DMA engine is done being used. This - allows multiple drivers to use the same DMA engine safely. - </para> - </section> - <section> - <title>ao_dma_abort</title> - <programlisting> - void - ao_dma_abort(uint8_t id) - </programlisting> - <para> - Terminate any in-progress DMA transaction, marking its - 'done' variable with the AO_DMA_ABORTED bit. - </para> - </section> - </section> - </chapter> - <chapter> - <title>Stdio interface</title> - <para> - AltOS offers a stdio interface over USB, serial and the RF - packet link. This provides for control of the device locally or - remotely. This is hooked up to the stdio functions by providing - the standard putchar/getchar/flush functions. These - automatically multiplex the available communication channels; - output is always delivered to the channel which provided the - most recent input. - </para> - <section> - <title>putchar</title> - <programlisting> - void - putchar(char c) - </programlisting> - <para> - Delivers a single character to the current console - device. - </para> - </section> - <section> - <title>getchar</title> - <programlisting> - char - getchar(void) - </programlisting> - <para> - Reads a single character from any of the available - console devices. The current console device is set to - that which delivered this character. This blocks until - a character is available. - </para> - </section> - <section> - <title>flush</title> - <programlisting> - void - flush(void) - </programlisting> - <para> - Flushes the current console device output buffer. Any - pending characters will be delivered to the target device. - </para> - </section> - <section> - <title>ao_add_stdio</title> - <programlisting> - void - ao_add_stdio(char (*pollchar)(void), - void (*putchar)(char), - void (*flush)(void)) - </programlisting> - <para> - This adds another console device to the available - list. - </para> - <para> - 'pollchar' returns either an available character or - AO_READ_AGAIN if none is available. Significantly, it does - not block. The device driver must set 'ao_stdin_ready' to - 1 and call ao_wakeup(&ao_stdin_ready) when it receives - input to tell getchar that more data is available, at - which point 'pollchar' will be called again. - </para> - <para> - 'putchar' queues a character for output, flushing if the output buffer is - full. It may block in this case. - </para> - <para> - 'flush' forces the output buffer to be flushed. It may - block until the buffer is delivered, but it is not - required to do so. - </para> - </section> - </chapter> - <chapter> - <title>Command line interface</title> - <para> - AltOS includes a simple command line parser which is hooked up - to the stdio interfaces permitting remote control of the device - over USB, serial or the RF link as desired. Each command uses a - single character to invoke it, the remaining characters on the - line are available as parameters to the command. - </para> - <section> - <title>ao_cmd_register</title> - <programlisting> - void - ao_cmd_register(__code struct ao_cmds *cmds) - </programlisting> - <para> - This registers a set of commands with the command - parser. There is a fixed limit on the number of command - sets, the system will panic if too many are registered. - Each command is defined by a struct ao_cmds entry: - <programlisting> - struct ao_cmds { - char cmd; - void (*func)(void); - const char *help; - }; - </programlisting> - 'cmd' is the character naming the command. 'func' is the - function to invoke and 'help' is a string displayed by the - '?' command. Syntax errors found while executing 'func' - should be indicated by modifying the global ao_cmd_status - variable with one of the following values: - <variablelist> - <varlistentry> - <term>ao_cmd_success</term> - <listitem> - <para> - The command was parsed successfully. There is no - need to assign this value, it is the default. - </para> - </listitem> - </varlistentry> - <varlistentry> - <term>ao_cmd_lex_error</term> - <listitem> - <para> - A token in the line was invalid, such as a number - containing invalid characters. The low-level - lexing functions already assign this value as needed. - </para> - </listitem> - </varlistentry> - <varlistentry> - <term>ao_syntax_error</term> - <listitem> - <para> - The command line is invalid for some reason other - than invalid tokens. - </para> - </listitem> - </varlistentry> - </variablelist> - </para> - </section> - <section> - <title>ao_cmd_lex</title> - <programlisting> - void - ao_cmd_lex(void); - </programlisting> - <para> - This gets the next character out of the command line - buffer and sticks it into ao_cmd_lex_c. At the end of the - line, ao_cmd_lex_c will get a newline ('\n') character. - </para> - </section> - <section> - <title>ao_cmd_put16</title> - <programlisting> - void - ao_cmd_put16(uint16_t v); - </programlisting> - <para> - Writes 'v' as four hexadecimal characters. - </para> - </section> - <section> - <title>ao_cmd_put8</title> - <programlisting> - void - ao_cmd_put8(uint8_t v); - </programlisting> - <para> - Writes 'v' as two hexadecimal characters. - </para> - </section> - <section> - <title>ao_cmd_white</title> - <programlisting> - void - ao_cmd_white(void) - </programlisting> - <para> - This skips whitespace by calling ao_cmd_lex while - ao_cmd_lex_c is either a space or tab. It does not skip - any characters if ao_cmd_lex_c already non-white. - </para> - </section> - <section> - <title>ao_cmd_hex</title> - <programlisting> - void - ao_cmd_hex(void) - </programlisting> - <para> - This reads a 16-bit hexadecimal value from the command - line with optional leading whitespace. The resulting value - is stored in ao_cmd_lex_i; - </para> - </section> - <section> - <title>ao_cmd_decimal</title> - <programlisting> - void - ao_cmd_decimal(void) - </programlisting> - <para> - This reads a 32-bit decimal value from the command - line with optional leading whitespace. The resulting value - is stored in ao_cmd_lex_u32 and the low 16 bits are stored - in ao_cmd_lex_i; - </para> - </section> - <section> - <title>ao_match_word</title> - <programlisting> - uint8_t - ao_match_word(__code char *word) - </programlisting> - <para> - This checks to make sure that 'word' occurs on the command - line. It does not skip leading white space. If 'word' is - found, then 1 is returned. Otherwise, ao_cmd_status is set to - ao_cmd_syntax_error and 0 is returned. - </para> - </section> - <section> - <title>ao_cmd_init</title> - <programlisting> - void - ao_cmd_init(void - </programlisting> - <para> - Initializes the command system, setting up the built-in - commands and adding a task to run the command processing - loop. It should be called by 'main' before ao_start_scheduler. - </para> - </section> - </chapter> - <chapter> - <title>USB target device</title> - <para> - AltOS contains a full-speed USB target device driver. It can be - programmed to offer any kind of USB target, but to simplify - interactions with a variety of operating systems, AltOS provides - only a single target device profile, that of a USB modem which - has native drivers for Linux, Windows and Mac OS X. It would be - easy to change the code to provide an alternate target device if - necessary. - </para> - <para> - To the rest of the system, the USB device looks like a simple - two-way byte stream. It can be hooked into the command line - interface if desired, offering control of the device over the - USB link. Alternatively, the functions can be accessed directly - to provide for USB-specific I/O. - </para> - <section> - <title>ao_usb_flush</title> - <programlisting> - void - ao_usb_flush(void); - </programlisting> - <para> - Flushes any pending USB output. This queues an 'IN' packet - to be delivered to the USB host if there is pending data, - or if the last IN packet was full to indicate to the host - that there isn't any more pending data available. - </para> - </section> - <section> - <title>ao_usb_putchar</title> - <programlisting> - void - ao_usb_putchar(char c); - </programlisting> - <para> - If there is a pending 'IN' packet awaiting delivery to the - host, this blocks until that has been fetched. Then, this - adds a byte to the pending IN packet for delivery to the - USB host. If the USB packet is full, this queues the 'IN' - packet for delivery. - </para> - </section> - <section> - <title>ao_usb_pollchar</title> - <programlisting> - char - ao_usb_pollchar(void); - </programlisting> - <para> - If there are no characters remaining in the last 'OUT' - packet received, this returns AO_READ_AGAIN. Otherwise, it - returns the next character, reporting to the host that it - is ready for more data when the last character is gone. - </para> - </section> - <section> - <title>ao_usb_getchar</title> - <programlisting> - char - ao_usb_getchar(void); - </programlisting> - <para> - This uses ao_pollchar to receive the next character, - blocking while ao_pollchar returns AO_READ_AGAIN. - </para> - </section> - <section> - <title>ao_usb_disable</title> - <programlisting> - void - ao_usb_disable(void); - </programlisting> - <para> - This turns off the USB controller. It will no longer - respond to host requests, nor return characters. Calling - any of the i/o routines while the USB device is disabled - is undefined, and likely to break things. Disabling the - USB device when not needed saves power. - </para> - <para> - Note that neither TeleDongle nor TeleMetrum are able to - signal to the USB host that they have disconnected, so - after disabling the USB device, it's likely that the cable - will need to be disconnected and reconnected before it - will work again. - </para> - </section> - <section> - <title>ao_usb_enable</title> - <programlisting> - void - ao_usb_enable(void); - </programlisting> - <para> - This turns the USB controller on again after it has been - disabled. See the note above about needing to physically - remove and re-insert the cable to get the host to - re-initialize the USB link. - </para> - </section> - <section> - <title>ao_usb_init</title> - <programlisting> - void - ao_usb_init(void); - </programlisting> - <para> - This turns the USB controller on, adds a task to handle - the control end point and adds the usb I/O functions to - the stdio system. Call this from main before - ao_start_scheduler. - </para> - </section> - </chapter> - <chapter> - <title>Serial peripherals</title> - <para> - The CC1111 provides two USART peripherals. AltOS uses one for - asynch serial data, generally to communicate with a GPS device, - and the other for a SPI bus. The UART is configured to operate - in 8-bits, no parity, 1 stop bit framing. The default - configuration has clock settings for 4800, 9600 and 57600 baud - operation. Additional speeds can be added by computing - appropriate clock values. - </para> - <para> - To prevent loss of data, AltOS provides receive and transmit - fifos of 32 characters each. - </para> - <section> - <title>ao_serial_getchar</title> - <programlisting> - char - ao_serial_getchar(void); - </programlisting> - <para> - Returns the next character from the receive fifo, blocking - until a character is received if the fifo is empty. - </para> - </section> - <section> - <title>ao_serial_putchar</title> - <programlisting> - void - ao_serial_putchar(char c); - </programlisting> - <para> - Adds a character to the transmit fifo, blocking if the - fifo is full. Starts transmitting characters. - </para> - </section> - <section> - <title>ao_serial_drain</title> - <programlisting> - void - ao_serial_drain(void); - </programlisting> - <para> - Blocks until the transmit fifo is empty. Used internally - when changing serial speeds. - </para> - </section> - <section> - <title>ao_serial_set_speed</title> - <programlisting> - void - ao_serial_set_speed(uint8_t speed); - </programlisting> - <para> - Changes the serial baud rate to one of - AO_SERIAL_SPEED_4800, AO_SERIAL_SPEED_9600 or - AO_SERIAL_SPEED_57600. This first flushes the transmit - fifo using ao_serial_drain. - </para> - </section> - <section> - <title>ao_serial_init</title> - <programlisting> - void - ao_serial_init(void) - </programlisting> - <para> - Initializes the serial peripheral. Call this from 'main' - before jumping to ao_start_scheduler. The default speed - setting is AO_SERIAL_SPEED_4800. - </para> - </section> - </chapter> - <chapter> - <title>CC1111 Radio peripheral</title> - <section> - <title>Radio Introduction</title> - <para> - The CC1111 radio transceiver sends and receives digital packets - with forward error correction and detection. The AltOS driver is - fairly specific to the needs of the TeleMetrum and TeleDongle - devices, using it for other tasks may require customization of - the driver itself. There are three basic modes of operation: - <orderedlist> - <listitem> - <para> - Telemetry mode. In this mode, TeleMetrum transmits telemetry - frames at a fixed rate. The frames are of fixed size. This - is strictly a one-way communication from TeleMetrum to - TeleDongle. - </para> - </listitem> - <listitem> - <para> - Packet mode. In this mode, the radio is used to create a - reliable duplex byte stream between TeleDongle and - TeleMetrum. This is an asymmetrical protocol with - TeleMetrum only transmitting in response to a packet sent - from TeleDongle. Thus getting data from TeleMetrum to - TeleDongle requires polling. The polling rate is adaptive, - when no data has been received for a while, the rate slows - down. The packets are checked at both ends and invalid - data are ignored. - </para> - <para> - On the TeleMetrum side, the packet link is hooked into the - stdio mechanism, providing an alternate data path for the - command processor. It is enabled when the unit boots up in - 'idle' mode. - </para> - <para> - On the TeleDongle side, the packet link is enabled with a - command; data from the stdio package is forwarded over the - packet link providing a connection from the USB command - stream to the remote TeleMetrum device. - </para> - </listitem> - <listitem> - <para> - Radio Direction Finding mode. In this mode, TeleMetrum - constructs a special packet that sounds like an audio tone - when received by a conventional narrow-band FM - receiver. This is designed to provide a beacon to track - the device when other location mechanisms fail. - </para> - </listitem> - </orderedlist> - </para> - </section> - <section> - <title>ao_radio_set_telemetry</title> - <programlisting> - void - ao_radio_set_telemetry(void); - </programlisting> - <para> - Configures the radio to send or receive telemetry - packets. This includes packet length, modulation scheme and - other RF parameters. It does not include the base frequency - or channel though. Those are set at the time of transmission - or reception, in case the values are changed by the user. - </para> - </section> - <section> - <title>ao_radio_set_packet</title> - <programlisting> - void - ao_radio_set_packet(void); - </programlisting> - <para> - Configures the radio to send or receive packet data. This - includes packet length, modulation scheme and other RF - parameters. It does not include the base frequency or - channel though. Those are set at the time of transmission or - reception, in case the values are changed by the user. - </para> - </section> - <section> - <title>ao_radio_set_rdf</title> - <programlisting> - void - ao_radio_set_rdf(void); - </programlisting> - <para> - Configures the radio to send RDF 'packets'. An RDF 'packet' - is a sequence of hex 0x55 bytes sent at a base bit rate of - 2kbps using a 5kHz deviation. All of the error correction - and data whitening logic is turned off so that the resulting - modulation is received as a 1kHz tone by a conventional 70cm - FM audio receiver. - </para> - </section> - <section> - <title>ao_radio_idle</title> - <programlisting> - void - ao_radio_idle(void); - </programlisting> - <para> - Sets the radio device to idle mode, waiting until it reaches - that state. This will terminate any in-progress transmit or - receive operation. - </para> - </section> - <section> - <title>ao_radio_get</title> - <programlisting> - void - ao_radio_get(void); - </programlisting> - <para> - Acquires the radio mutex and then configures the radio - frequency using the global radio calibration and channel - values. - </para> - </section> - <section> - <title>ao_radio_put</title> - <programlisting> - void - ao_radio_put(void); - </programlisting> - <para> - Releases the radio mutex. - </para> - </section> - <section> - <title>ao_radio_abort</title> - <programlisting> - void - ao_radio_abort(void); - </programlisting> - <para> - Aborts any transmission or reception process by aborting the - associated DMA object and calling ao_radio_idle to terminate - the radio operation. - </para> - </section> - <section> - <title>Radio Telemetry</title> - <para> - In telemetry mode, you can send or receive a telemetry - packet. The data from receiving a packet also includes the RSSI - and status values supplied by the receiver. These are added - after the telemetry data. - </para> - <section> - <title>ao_radio_send</title> - <programlisting> - void - ao_radio_send(__xdata struct ao_telemetry *telemetry); - </programlisting> - <para> - This sends the specific telemetry packet, waiting for the - transmission to complete. The radio must have been set to - telemetry mode. This function calls ao_radio_get() before - sending, and ao_radio_put() afterwards, to correctly - serialize access to the radio device. - </para> - </section> - <section> - <title>ao_radio_recv</title> - <programlisting> - void - ao_radio_recv(__xdata struct ao_radio_recv *radio); - </programlisting> - <para> - This blocks waiting for a telemetry packet to be received. - The radio must have been set to telemetry mode. This - function calls ao_radio_get() before receiving, and - ao_radio_put() afterwards, to correctly serialize access - to the radio device. This returns non-zero if a packet was - received, or zero if the operation was aborted (from some - other task calling ao_radio_abort()). - </para> - </section> - </section> - <section> - <title>Radio Direction Finding</title> - <para> - In radio direction finding mode, there's just one function to - use - </para> - <section> - <title>ao_radio_rdf</title> - <programlisting> - void - ao_radio_rdf(int ms); - </programlisting> - <para> - This sends an RDF packet lasting for the specified amount - of time. The maximum length is 1020 ms. - </para> - </section> - </section> - <section> - <title>Radio Packet Mode</title> - <para> - Packet mode is asymmetrical and is configured at compile time - for either master or slave mode (but not both). The basic I/O - functions look the same at both ends, but the internals are - different, along with the initialization steps. - </para> - <section> - <title>ao_packet_putchar</title> - <programlisting> - void - ao_packet_putchar(char c); - </programlisting> - <para> - If the output queue is full, this first blocks waiting for - that data to be delivered. Then, queues a character for - packet transmission. On the master side, this will - transmit a packet if the output buffer is full. On the - slave side, any pending data will be sent the next time - the master polls for data. - </para> - </section> - <section> - <title>ao_packet_pollchar</title> - <programlisting> - char - ao_packet_pollchar(void); - </programlisting> - <para> - This returns a pending input character if available, - otherwise returns AO_READ_AGAIN. On the master side, if - this empties the buffer, it triggers a poll for more data. - </para> - </section> - <section> - <title>ao_packet_slave_start</title> - <programlisting> - void - ao_packet_slave_start(void); - </programlisting> - <para> - This is available only on the slave side and starts a task - to listen for packet data. - </para> - </section> - <section> - <title>ao_packet_slave_stop</title> - <programlisting> - void - ao_packet_slave_stop(void); - </programlisting> - <para> - Disables the packet slave task, stopping the radio receiver. - </para> - </section> - <section> - <title>ao_packet_slave_init</title> - <programlisting> - void - ao_packet_slave_init(void); - </programlisting> - <para> - Adds the packet stdio functions to the stdio package so - that when packet slave mode is enabled, characters will - get send and received through the stdio functions. - </para> - </section> - <section> - <title>ao_packet_master_init</title> - <programlisting> - void - ao_packet_master_init(void); - </programlisting> - <para> - Adds the 'p' packet forward command to start packet mode. - </para> - </section> - </section> - </chapter> -</book> |