Serial Terminal

Some notes about how to turn an ATtiny2313 AVR microcontroller, an HD44780 display and an AT keyboard into a Bifferboard console.

AVR Crystal Frequency

Care must be taken to chose the right crystal, 18432000Hz allows precisely matching 115200 baud, which is the Bifferboard default.

ATtiny2313 pinouts

ATmega168 pinouts

HD44780 pinouts

HD44780 connection

AVR and HD44780 powered from 5v

Reset, SCL, MISO and MOSI are kept free for in-system programming

PB0-3 Are connected to DB4-7 for LCD data

RXD/TXD are connected to the Bifferboard (TXD operated in pull-down mode to be compatible with Bifferboard input).

PD4 --> E

PD5 --> RS

R/W permanently pulled low on HD44780