Canon-RC6-MCU

This project implements the protocol of the Canon-RC6 infrared remote controller on MCUs. The RC has a mode switch that can select instant or delayed (2 seconds) shutter. The software samples a GPIO on the beginning and decides the mode based on this GPIO's input state.

This is a standalone application. It sends the IR message and turns of the microcontroller which is ideal for battery supplied applications. Before starting transmitting the message the software waits 10ms which cames handy as a power debounce.

Protocol

The project is based on this article.

The protocol is quite simple. It stars and ends with a burst of 18 pulses and the length of the delay between these two bursts selects the shutter mode.

The period of each pulse is 29.3us (34.1kHz) and the high time is 9.3us. The instant shutter mode has a delay of 7.1ms and the delayed shutter mode operates with 5.3ms gap between the bursts.

Build

make PLATFORM=<stm32f4xx|lpc8xx> all

Build targets

• all - Builds the project
• clean - Removes build directory
• deploy - Uploads the binary using OpenOCD
• debug - Uploads the binary using OpenOCD and goes into debug mode
• gdb - Starts gdb and connects to OpenOCD gdb server

Platforms

The project handles multiple hardware platforms.

Platform	IR out	Mode select
STM32F4xx	PD12	PA0
LPC8xx	PIO0_0	PIO0_4

Platform interface

• Startup/startup_[platform].S - MCU startup file
• platform_macros.h
  • NANOSEC_TO_COUNTER(ns) - Converts nanosecs to raw timer value
  • Timer_IRQHandler - Name of the timer interrupt handler function
• platform_[platform].c - Platform dependent function implementations
  • init_gpio - Initializes mode select and IR out GPIO
  • init_timer - Configures timer and sets the period
  • init_interrupt - Enables timer interrupt
  • is_instant_mode - Return the mode select value
  • set_active_count - Sets the length of the high time of the timer output
  • clear_timer_interrupt - Clears timer interrupt
  • power_down - Powers down the MCU
• [platform].ld - Linker script
• openocd.cfg - OpenOCD configuration file

Possible improvements

• GPIO configuration could come from a config header