The Expander is a 2-layer 181 x 108mm optional board that serves a dual role in the Z20X system. It plugs on to the expansion header, and provides the system with three extra slots for additional modules in the Z20X’s native module format with 72 pins and 3.3V logic. In addition to that, it also offers three more slots for RC2014-compatible modules with 80 pins and 5V logic. If support for the RC2014 bus is not needed, all components on the board can be reduced to only J1-J4 and C1-C4 installed.
There is not much on the PCB in terms of components – except the connectors, a few capacitors, one 3.3V LDO, several resistor networks, and three multi-channel level shifters. The level shifters are the only SMT components on the PCB. For easiest assembly the SMT components should be the first ones soldered on the PCB.
Schematic for the Expander can be seen in the picture below. It can also be downloaded as a PDF file.
PCB gerbers can be downloaded as well and sent for manufacturing.
The Expander serves a secondary role as a mechanical stand for the main assembly. It holds it from behind to allow the display in vertical position.