This is alternative firmware for model radio FlySky FS-TH9X and clones.
This software comes with absolutely NO-WARRANTY.



It is programmed with using possibilities of hardware, using timers,
interrupts and cooperative multitasking (this is because it is much
simplier to program it then).

It was written for Cosmic C compiler and will need changes to support
other compilers.





There are 2 interrupts:

ppm_interrupt
    - timer3 update interrupt
    - sets values for next servo channel to timer
    - wakeups task CALC during SYNC signal
timer_interrupt
    - timer2 overflow
    - every 5ms
    - increments time from start
    - count LCD blink time and wakeups task LCD
    - handles buzzer
    - wakeups task INPUT
    - handles task MENU delay and wakeups this task




There are 4 tasks:

LCD
    - is doing actual write to LCD controller
    - is waked up by lcd_update(), lcd_clear()
    - is waked up from timer to do automatic blinking
INPUT
    - is doing reading of ADC values and key matrix
    - is waked up from timer every 5ms
CALC
    - is computing values for each servo and sync signal
    - is waked up from ppm interrupt during sync signal generation
    - also nedded to wakeup after changing number of PPM channels in MENU
MENU
    - is main program handling keys, menus, lcd
    - is waked up from timer when menu_delay expired
    - is waked up from INPUT task when
	- buttons state changed
	- MENU task wanted ADC values (for calibrate) or battery voltage
	- status of battery low changed




Files:

stm8.h		- macros for STM8 handling
gt3b.h		- global common values

vector.c,h	- table of interrupt vectors
task.c,h	- cooperative multitasking
buzzer.c,h	- buzzer
eeprom.c,h	- eeprom read/write
timer.c,h	- timer 5ms
input.c,h	- INPUT task, reading ADC and keys
lcd.c,h		- LCD task, writing to LCD controller, blinking
ppm.c,h		- generating of PPM signal
main.c,h	- initialize all and call MENU task

config.c,h	- global and model configuration
menu.c,h	- MENU task, handling keys, menus, lcd
calc.c,h	- CALC task, calculate PPM values


Only last 3 files are used to implement what means what button
and how it changes signal for servos. Other files are sort of libraries
(or it can be viewed as a little operating system :-)