Fg3avr is 3 channels frequency generator for arduino (or any other board with ATMEGA328P) which can be used for multiple purposes.

Features

• Frequencies outputs are digital, the pins used for output are D2, D3, D4
• Generator is driven by UART commads. The UART pins are default D0 and D1
• The frequencies are adjustable by startup delay, 'off' period and 'on' period
• The generation can be turned on and off independently for each channel
• Current frequencies can be stored in eeprom and loaded from eeprom.
• At board power-up it checks if there are frequencies stored in eeprom. They are loaded from eeprom and generation starts automaticly, no need to connect and use UART

UART commands

Each command contains additional CRC bytes at the end. The checksum algorithm used is CRC16/MODBUS.
All timings are 16 bit values (2 bytes). These timing values are measured in time units of 21/16000000 seconds, that is 1.3125 micro seconds per one unit.
The UART speed is 19200 bps.

• Command 00 - PING PONG
  Used to check if board is connected and alive

  0x00	0x40	0xBF

• Command 01 - SET FREQUENCIES
  if ON period equals to 0 then frequency is muted (off)
  Command contains 21 bytes. F1, F2, F3 - three frequencies

	0x01
DELAY for F1	H byte L byte
ON period for F1	H byte L byte
OFF period for F1	H byte L byte
DELAY for F2	H byte L byte
ON period for F2	H byte L byte
OFF period for F2	H byte L byte
DELAY for F3	H byte L byte
ON period for F3	H byte L byte
OFF period for F3	H byte L byte
CRC16 Checksum	H byte of CRC L byte of CRC

• Command 02 - STORE TO EEPROM
  Stores current frequencies to eeprom

  0x02	0x81	0x3E

• Command 03 - LOAD FROM EEPROM
  Loads frequencies from eeprom, this is done also at the reset (startup)

  0x03	0x41	0xFF

• Possible responses from arduino:
  All respones are 3 byte long

  OK, COMMAND EXECUTED

  0x00	CRC16 H byte	CRC16 L byte

  BAD COMMAND (CRC ERROR)

  0x01	CRC16 H byte	CRC16 L byte

  BAD DATA IN EEPROM (CRC ERROR)

  0x01	CRC16 H byte	CRC16 L byte