path: root/cctools/s51/s51.1

.\"
.\" Copyright © 2009 Keith Packard <keithp@keithp.com>
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.\" it under the terms of the GNU General Public License as published by
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.\" General Public License for more details.
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.\"
.TH S51 1 "s51" ""
.SH NAME
s51 \- hex debugger for cc1111 processors
.SH SYNOPSIS
.B "s51"
[\-t \fIcpu-type\fP]
[\-X \fIfrequency\fP]
[\-c]
[\-r \fIlisten-port\fP]
[\-Z \fIlisten-port\fP]
[\-s]
[\-S]
[\-p \fIprompt\fP]
[\-V]
[\-v]
[\-H]
[\-h]
[\-m]
.SH DESCRIPTION
.I s51
connects to a cc1111 processor through a cp1203-based USB-to-serial
converter board, using the GPIO pins available on that chip. It provides an
interface compatible with the 8051 emulator of the same name (s51), but
communicating with the real chip instead of an emulation. Using a modified
version of the SDCC debugger (sdcdb), you can control program execution
on the target machine at source-level.

.SH OPTIONS
The command line options are designed to be compatible with the 8051
emulator so that it can be used with sdcdb. As such, they're all one letter
long.
.IP "\-t \fIcpu-type\fP"
The 8051 emulator can operate as one of several different chips. Oddly, the
real hardware cannot, so this option is ignored.
.IP "\-X \fIfrequency\fP"
Similarly, the emulator can pretend to run at an arbitrary frequency
which the real hardware cannot do. Ignored.
.IP "\-c"
.IP "\-s"
.IP "\-S"
.IP "\-v"
.IP "\-V"
All ignored.
.IP "\-r \fIlisten-port\fP, -Z \fIlisten-port\fP"
The emulator and sdcdb communicate through a network socket. This option
switches the debugger from communicating through stdin/stdout to listening
on a specific network port instead. Once a connection is made, the debugger
continues on, using that network port for command input and output. The
debugger uses port 9756, and attempts to connect before launching s51, so if
s51 is listening on this port before sdcdb is started, sdcdb will end up
talking to the existing s51 instance. That's often useful for debugging s51
itself.
.IP "\-p \fIprompt\fP"
This sets the command prompt to the specified string.
.IP "\-P"
This sets the command prompt to a single NUL character. This is for use by
sdcdb.
.IP "\-h"
This should print a usage message, but does nothing useful currently.
.IP "\-m"
This option is not present in the original 8051 emulator, and causes s51 to
dump all commands and replies that are received from and sent to sdcdb.
.SH COMMANDS
Once started, s51 connects to the cc1111 via the CP2103 using libusb2 and
then reads and executes commands, either from stdin, or the nework
connection to sdcdb.
.PP
Unlike the command line, s51 contains built-in help for each of these
commands, via the 'help' command. Most of the commands are available in a
long form and a single character short form. Below, the short form follows
the long form after a comma.
.IP "help, ? {command}"
Without arguments, prints a list of available commands. With an argument
prints more detail about the specific command
.IP "quit, q"
Terminates the application, without changing the state of the target
processor.
.IP "di [start] [end]"
Dumps imem (256 bytes of "internal" memory) from start to end (inclusive).
.IP "ds [start] [end]"
Dumps sprs from start to end (inclusive). Note that while most sprs are
visible in the global address space, some are not, so use this command
instead of "dx" to read them.
.IP "dx [start] [end]"
Dump external (global) memory from start to end (inclusive).
.IP "set, t <prefix> [start] {data ...}"
Store to the memory space specified by prefix where prefix is one of "xram",
"rom", "iram", or "sfr". Store bytes starting at start.
.IP "dump, d <prefix> [start] [end]"
Dump from the memory space specified by prefix, where prefix is one of
"xram", "rom", "iram" or "sfr". Dumps from start to end (inclusive).
.IP "file [filename]"
Specifies an intel-format hex file (ihx) that contains the contents of the
rom area loaded into the cc1111. This is used to respond to requests to dump
rom memory contents without getting them from the cc1111 (which is slow).
.IP "pc, p {address}"
If the address argument is given, this sets the program counter to the
specified value. Otherwise, the current program counter value is displayed.
.IP "break, b [address]"
Sets a breakpoint at the specified address. This uses the built-in hardware
breakpoint support in the cc1111. As a result, it supports no more than four
breakpoints at once. You must therefore use a modified version of sdcdb which
changes how program execution is controlled to work within this limit.
.IP "clear, c [address]"
Clear a breakpoint from the specified address.
.IP "run, r, go, g {start} {stop}"
Resumes execution of the program. If the start argument is present, then it
begins at that address, otherwise it continues running at the current pc. If
a stop argument is present, then a temporary breakpoint is set at that
address. This temporary breakpoint will be removed when execution hits it.
.IP "next, n"
Step one instruction. In the original s51 program this would ignore
subroutines, but as sdcdb doesn't require this functionality, it's not
available here.
.IP "step, s"
Step one instruction.
.IP "load, l [filename]"
This is not implemented, but it is supposed to load a hex file into flash.
Use the ccload program instead.
.IP "halt, h"
Halt the processor. This is the only command which can be sent while the
program is running. It is ignored at other times.
.IP "reset, res"
Reset the processor. This pulls the reset pin low and re-enables debug mode.
Check the cc1111 documentation to see precisely what this does.
.IP "status"
This dumps the cc1111 debug status register.
.IP "info, i breakpoints, b"
List the current breakpoints.
.IP "info, i help, ?"
List the things you can get info on.
.IP "stop"
This doesn't do anything and is present only to retain compatibility with
the original 8051 emulator.
.SH "BOARD BRINGUP DEBUGGING"
.PP
While the original purpose for this program was to connect the source
debugger with the hardware, it can also be used as a low-level hex debugger
all on its own. In particular, all of the cc1111 peripherals can be
manipulated directly from the s51 command line.
.IP "Starting s51"
If the CP2103 is plugged in, and the CC1111 is connected correctly, the
\'s51\' command itself should connect to the device without trouble.
Note that the CP2103 must have the GPIO pins configured correctly as well.
.IP
$ s51
.br
Welcome to the non-simulated processor
.br
> status
.br
	CPU halted
.br
	Halted by debug command
.br
>
.IP "Turning on LEDs"
Two of the cc1111 GPIO pins, P1_0 and P1_1 are capable of driving external
LEDs. To control these, set the Port 1 direction bits to make these output
pins and then change the Port 1 data to set them high or low:
.IP
> set sfr 0xfe 0x02	# set P1DIR to 0x2
.br
> set sfr 0x90 0x02	# set P1_1 to high
.br
> set sfr 0x90 0x00	# set P1_1 to low
.IP "Reading the A/D converters"
The six A/D converter inputs can each be connected to any of the P0 pins,
ground, the A/D voltage refernece, an internal temperature sensor or VDD/3.
To read one of these values, select an A/D converter to use then start the
conversion process. The cc1111 manual has the table for selecting the input
on page 144.
.IP
To configure one of the P0 pins for use by the A/D unit, we program the
ADCCFG register, setting the bits in that which match the pins desired:
.IP
> set sfr 0xf2 0x3f	# enable all 6 A/D inputs
.IP
To trigger a single conversion, we ask the A/D unit to perform an 'extra'
conversion, which means to do a single conversion not a whole sequence of
conversions. This is controlled by the ADCCON3 register at 0xB6:
.IP
> set sfr 0xb6 0xb2	# sample P0_2 using 12 bits of precision
.br
> ds 0xba 0xbb		# dump the ADC data low and high regs
.br
> set sfr 0xb6 0xbe	# sample internal temperature sensor
.br
> ds 0xba 0xbb		# dump the ADC data low and high regs
.SH "SEE ALSO"
sdcdb(1), ccload(1)
.SH AUTHOR
Keith Packard