addon_gpio

GPIO add-on board for the large camper add-on slot. The board expands the camper node with an MCP23S17 SPI port expander, providing 16 digital inputs or outputs.

Function

  • MCP23S17 in SO package as a 16-bit GPIO expander.
  • SPI connection via MOSI, MISO, SCK, and GPIO_CS from the add-on slot.
  • The expander’s reset line is connected to RESET from the add-on slot.
  • Two 2x5 pin headers expose the GPIO banks GPA and GPB.
  • P5V and GND are also available on the GPIO headers.
  • Three solder jumpers with pull-down resistors configure address pins A0 to A2.

Controller Interface

The MCP23S17 operates on the camper node’s SPI bus. SDA_MOSI_TX is used as MOSI/SI, SCL_MISO_RX as MISO/SO, SCK comes directly from the add-on slot, and GPIO_CS selects the device. The RESET line resets the expander together with the add-on system.

GPIO Headers

JP5 exposes bank GPA0 to GPA7 as well as P5V and GND. JP4 exposes bank GPB0 to GPB7 as well as P5V and GND. This makes it possible to connect simple digital extensions, small control panels, or additional signals to the camper node without extra logic.

Addressing

JP1 to JP3 switch the MCP23S17 address pins A0 to A2 to P5V. With the jumpers left open, R1 to R3 pull the address pins down to GND. This allows the SPI hardware address of the expander to be adjusted when needed.

board images

board_both.png
board_bottom.png
board_bottom_flopped.png
board_top.png