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TeleMetrum Low-level Access
CC1111 4-wire debug interface:
debug data, debug clock, reset, ground
CP2103 -- 4 GPIOs controlled from USB
One USB packet per half clock
Beagle USB hardware monitor
CC1111-based debug link
emulates serial on USB
provides high-level commands
TeleMetrum Software Development Environment
Small Device C Compiler, targeting 8051 CPU
Source Debugger for SDCC
Hex debugger using either CP2103 or CC1111 link
Emulates mcs51 emulator
Except talks to real hardware
Hooks up to sdcdb
AltOS architecture
Multi-threaded
Avoids the 'one big loop'
Non pre-emptive
Limits where pre-emption can occur
sleep/wakeup rendezvous
Good enough for Linux
Timers, mutexes
Basic OS services
Flight software architecture
Flight progress tracked through discrete states
Pad - Sitting vertically
Boost
Acceleration > 2g and Speed > 5m/s
or
Height > +20m
Fast
Acceleration < -1/4g
or
Boost period > 15s
Coast
Speed < 200m/s
or
Height < Max_height - 500m
Apogee
Height < Max Height - 10m
Main
Height < Main Height
Land
Acceleration stable for 5 seconds
Height stable for 5 seconds
Height < Launch height + 1000m
Calibration
Radio calibrated by adjusting PLL against freq counter
48MHz crystal good to 20ppm
20ppm at 434MHz is 9Khz
Accelerometer calibrated by rotating board on bench
Accelerometer output runs through 5V->3.3V divider
Uses 1% resistors
Also automatically adjusts for 100G/50G/40G devices
GPS adventures
Problem: GPS looses satellites during boost phase
GPS receivers track sats by synthesizing expected signal
frequency based on relative velociy
phase based on distance
Change in actual signal means changing synthetic signal
High acceleration means allowing faster changes
Change rate limited by 'loop filter' bandwidth.
Drag race plots
Standard flight plot set
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