read all 8-channels on MCP3304 for testing https://github.com/fivdi/mcp-spi-adc/pull/1

readall-mcp-spi-adc.js

'use strict';

var mcpadc = require('../');

function readadc(channel, cb) {
  var adc = mcpadc.openMcp3304(channel, {speedHz: 20000}, function (err) {
    if (err) throw err;

    adc.read(cb);
  });
}

for (var i = 0; i < 8; ++i) {
  readadc(i, function(i, err, reading) {
    console.log(i + ' = ' + (reading.value * 3.3));
  }.bind(null, i));
}