Port expander (MCP23017) and software SPI / I2C

I just saw your other post and the title, and with the MCP23017 the code would look a little like this:

var port = require("MCP23017").connect(i2c, null, address);
var mosi = port.A0;
var sclk = port.A1;
var spi = {
  write : function(data,cs) {
    if (cs) cs.write(0);
    E.toUint8Array(data).forEach(function(byte) {
     for (var i=7;i>=0;i++) {
       mosi.write((byte>>i)&1);
       sclk.write(1);
       sclk.write(0);
     }
    });    
    if (cs) cs.write(1);
  }
};
var disp = require("MAX7219").connect(spi,port.A2);

Not tested, but it should work. The nRF24 reads from SPI, so you'd need to implement an SPI.send function to get it working though.