The design is based on the old Raspberry Pi B Serial Expansion Board. The electronics are updated and several functions are added. Dimensions of the expansion unit: 65 mm x 56.5 mm, standard dimensions of an Raspberry Pi HAT expansion unit
GPIO function expansion:
- 16 independent GPIO interfaces each with power supply and earthing (3V3 level)
- 2 independent SPI interfaces
- I2C interface
- Standard RS232 interface
- Infra-red Reciever
Features a RS232 interface is for connection to PC, and other devices. The Raspberry Pi serial interface with TTL-Levels is offered, and does not support the connection with PC directly. Also includes an onboard power supply regulator.
Raspberry Pi GPIO UART Expansion Board , with 2 x SPI, 1 x I2C, & RS232, is readily available on eBay for around $10.00.