Custard pi system custard pi custard pi 6 ready built this custard pi extension card provides a facility for a raspberry pi to have control of up to 8x relays connection is via a supplied ribbon cable with the cable plugging into the extension card and the gpio interface of the raspberry pi screw terminals are provided to access the three pins common no nc of each relay and each relay has an led to conform operations when the card is plugged in via the ribbon cable a led on the 33v