Fg3avr is 3 channels frequency generator for arduino with ATMEGA328P mcu. It can be used for various purposes, for example, it can drive 3 phase motors or can be used for 3 phase AC generation

Features

• Frequency outputs are digital, the pins used for output are D2, D3, D4
• Generator is driven by UART commads. UART pins used are default D0 and D1
• Each frequency has startup delay, 'on' period and 'off' period adjustable parameters. Also generation can be turned off independently for each channel
• Frequency parameters 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 automatically, no need to connect and setup by UART

Capabilities

This board has capabilities below

• Min timing units 1
• Max timing units 65535
• CPU ticks per one time unit 21
• CPU ticks per one second 16000000

So this device has 1.3125 micro seconds resolution per one unit. Max frequency it is able to generate is 378 kHz

UART commands

Each command contains additional CRC bytes at the end. The checksum algorithm used is CRC16/MODBUS.
UART protocol now is upgraded to support 32 bit timing ranges, but this generator has limited timing resolution up to 16 bits. The UART speed is 19200 bps. All values use big endian byte ordering (highest byte comes first)

• 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 39 bytes. F1, F2, F3 - three frequencies

  Command	0x01
  DELAY for F1	32 bit value
  ON period for F1	32 bit value
  OFF period for F1	32 bit value
  DELAY for F2	32 bit value
  ON period for F2	32 bit value
  OFF period for F2	32 bit value
  DELAY for F3	32 bit value
  ON period for F3	32 bit value
  OFF period for F3	32 bit value
  CRC16 Checksum	16 bits

• 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

• Command 04 - CHECK CAPABILITIES
  Request device capabilities (timing range, ticks per one unit, cpu ticks per second)

  0x04	0x83	0xBE

• Possible arduino responses:

  OK, COMMAND EXECUTED

  0x00	CRC checksum 16 bits

  BAD COMMAND (CRC ERROR)

  0x01	CRC checksum 16 bits

  BAD DATA IN EEPROM (CRC ERROR)

  0x02	CRC checksum 16 bits

  CAPABILITIES (Response to command 04)

  Command	0x04
  Min units 1	0x00	0x00	0x00	0x01
  Max units 65536	0x00	0x00	0xff	0xff
  Ticks per one unit 21	0x00	0x00	0x00	0x15
  CPU ticks per one second 16000000	0x00	0xf4	0x24	0x00
  CRC 16 bits	0x06	0x17