The example of connecting a PS/2 keyboard and USB keyboard with PS/2 COMBO mode support to ESP32-C3.
You need to build it with the release profile (i.e. cargo run --release) since otherwise the interrupt latency is too slow.
- 2 x 2.2kΩ resitors
- 2 x 120Ω resitors
Keyboard ESP32-C3
5V ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 5V
GND ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ GND
┏━━━━━┓
DATA ━━━━━━━━━━━━━━━━━━━━━┳━━━━━━┫ 120 ┣━━━ IO1
┃ ┗━━━━━┛
┏┻┓
┃2┃
┃.┃
┃2┃
┃k┃
┗┳┛
┃
┣━━━━━━━━━━━━━━━━ 3V3
┃
┏┻┓
┃2┃
┃.┃
┃2┃
┃k┃
┗┳┛
┃ ┏━━━━━┓
CLK ━━━━━━━━━━━━━━━━━━━━━┻━━━━━━┫ 120 ┣━━━ IO2
┗━━━━━┛
The pinout of PS/2 connector is available at Wikipedia.
Hint 1: use wire wrapping to connect wires to PS/2 connector
Hint 2: make sure to flip the PS/2 pinout if connecting to the male part the connector or to the back part of the connector.
The same circuit works with USB keyboards with PS/2 COMBO mode support. It's sufficient to replace PS/2 connector with USB connector according the schematics USB to PS2 schematics.
The example converts keyboard to serial which can be then consumed by other board. The receiver board can use pc-keyboard crate to decode signals. The following connection is used in RustZX-ESP32 project.
ESP32-C3 Converter ESP32-S3 Receiver
RX IO4 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ TX IO17
TX IO5 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ RX IO18
GND ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ GND
Run: cargo run --release --example keyboard_to_serial
Async implementation of the converter with Embassy.
Note: CPU must be clocked at 160MHz to decode values properly, the frequency 80 MHz is not sufficient.
Run: cargo run --release --example embassy_keyboard_to_serial --features embassy