FabFTDI

FabFTDI Projects

This repository contains all my FabFTDI projects: FabFTDI projects which make use of avr microcontrollers are based on the V-USB library from obdev and the AVR-CDC work done by K Ishikawa at recursion.jp.

A few points about the AVR-CDC protocol with Atmel microcontrollers - AVR-CDC enables a PC to communicate with a low-speed USB device (AVR microcontroller) through a virtual COM port.

The table below (from recursion.jp) lists the specifications for AVR-CDC with different AVR microcontrollers:

• AVR-CDC with USART (ATmega8/48/88/168/328)
  • speed: 600 - 38400 bps
  • datasize: 5 - 8 bits
  • parity: none/even/odd
  • stopbit: 1/2
  • controls: DTR, RTS, CTS
• AVR-CDC with USART (ATtiny2313)
  • speed: 600 - 38400 bps
  • datasize: 8
  • parity: none
  • stopbit: 1
• AVR-CDC without USART (ATtiny45/85)
  • speed: 1200 - 4800 bps
  • datasize: 8
  • stopbit: 1…

1. CH340G-based FabFTDI
   • speeds up to 2 Mbps (loopback)
   • tested up to 250 kbps with ESP8266 module
   • uses hardware USB-to-TTL chip
   • low cost (USD0.40 per IC for 10 pcs)
2. ATmega8-based FabFTDI
   • speeds up to 2 Mbps (loopback)
   • tested up to 250 kbps with ESP8266 module
   • hardware UART
   • uses V-USB/AVR-CDC library
3. ATtiny2313-based FabFTDI
   • speed up to 57600 bps
   • hardware UART
   • uses V-USB library
4. ATtiny45-based FabFTDI (w/crystal)
   • speeds up to 4800 bps
   • uses V-USB library
5. ATtiny45-based FabFTDI (w/internal PLL)
   • speeds up to 4800 bps
   • uses V-USB library

Collection of FabFTDI boards (from left): CH340g-based, ATmega8-based, ATtiny2313-based, ATtiny45-based w/crystal, ATtiny45-based w/internal oscillator

Copyright (c) Steven Chew…

MIT license