the Raspberry Pi 4 has six SPI controllers, six I2C controllers, and six UARTs – all on its 40-pin header. You can’t make use of all of these at once, but with up to four different connections ...

Raspberry Pi 3 Model A+ Kit From Vilros ... 2.4GHz and 5 GHz IEE 802.11b/g/n/ac wireless LAN, Bluetooth 4.2/BLE Access: Extended 40-pin GPIO header USB: One USB 2.0 Port - Keeping it compact ...

Other connections include PoE on a four-pin header, an ARM debug / UART ... rather than the wider one on the Pi 4. The Raspberry Pi 5 is, in some ways, a modest step forward.

Sequent Microsystems’ "Eight 24-bit ADC 8-layer Stackable HAT" is a Raspberry Pi expansion board designed for home automation ...