Not sure I understand? what's MCP-19/MCP-20?
What happens to the value from readPort if you connect up other pins of the MCP23S17 to 0 or 3.3v?
@Gordon started
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Not sure I understand? what's MCP-19/MCP-20?
What happens to the value from readPort if you connect up other pins of the MCP23S17 to 0 or 3.3v?