This module is specially designed for Raspberry Pi IO expansion Modules. It can effectively solve the problem, which is for Raspberry that can't send IO port sufficiently. And module uses four 74HC595 chips to expand 32 IO ports. As shown above, the top of the module will expand the IO for Raspberry Pi again that can be cascaded for more IO expansion modules to achieve theoretically unlimited expansion.Features:32 GPIO Expansion - This cascade expansion board supports 32 GPIO expansion. Infinity Connection - The IO extend adapter module is capable of connecting with same module infinitely. Wiring PI API & Sample Code - It uses wiring PI API and sample code. Stable Connection - SPI interface ensures the stability and smoothness of connection. 8-bit Input & Output - Adopting 8-bit serial input and 8-bit serial serial or parallel output to make data transmission super stable without stuck or cut. Port:-- for Raspberry Pi 2*13port-- for Raspberry Pi 2*13 cascade port--Q0-Q31 expanded IO portSpecifications:Working voltage: 2.4v-5vIO voltage: 3.3vExpanded 32 unidirectional IOConnection through SPI100 MHz( typical) shift out frequency8-bit serial input8-bit serial or parallel outputSpecified from -40C to +85C and from -40C to +125CTypical Application: Drive the lattice screen, Driver numeric display, Drive matrix LEDHow to Use:Insert the module that the silk screen says 'RPI IN'. Pay attention that don't make the direction reversed. The correct direction of insert module is above the for Raspberry Pi's PCB; The 8*4header in the module are Q0-Q31 expanded GPIO, they can connect to the peripheral through the Dupont Line. The header which near silk screen write 'EXT' expand GPIO for Raspberry Pi, user can cascade the other module or the same module.Package List:1 * GPIO Expansion Module.