Sequent Microsystems
Sequent Microsystems designs and manufactures I/O cards for the Raspberry Pi. We extend the capabilities of the Raspberry Pi with analog inputs and outputs (0-3.3V, 0-10V, 4-20mA), opto-isolated inputs from 3 to 240V AC or DC, 4 to 16 on-board relays and solid-state outputs, event counters, quadrature encoders, 1K/10K thermistors, RTD sensor inputs, real-time clock with battery backup, RS485/MODBUS communications, MOSFET and triac load drivers. All of our cards use only the I2C port to communicate with the Raspberry Pi, leaving all GPIO pins available for other tasks.