Our collection of I/O HATs for Raspberry Pi expands the capabilities of this single board computer with analog inputs and outputs (0-3.3V, 0-10V, 4-20mA), optically 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, Thermocouples, RTD sensor inputs, Real Time Clocks with battery backup, RS485/MODBUS and 1-Wire communication, MOSFET and TRIAC load drivers. All our cards use only the I2C port for communicating with Raspberry Pi, leaving all the GPIO pins available for other tasks. Three Sequent cards (Home, Building and Industrial Automation) are \"Swiss Army Knife\" types, packing all the possible functions in the available space. If extra functionality is desired, each card can be stacked up to eight levels. Build-in hardware watchdogs on all our \"smart\" cards can cycle the power on Raspberry Pi to ensure that mission critical projects recover if Raspberry Pi locks up. Additional universal inputs, relays or solid state outputs can be added using compatible cards. Up to eight cards of each type can be installed in almost any combination on a single Raspberry Pi.