NodeJS example using SPI communication to retrieve analog data through MCP3008 and Raspberry Pi

spi_example.js

var rpio = require('rpio');

rpio.spiBegin();
//rpio.spiChipSelect(0);				/* Chip select: use CE0 (default) */
//rpio.spiSetCSPolarity(0, rpio.LOW)	/* Commonly chip enable (CE) pins are active low, and this is the default. */
//rpio.spiSetClockDivider(256)			/* MCP3008 max is ~1MHz, 256 == 0.98MHz */
//rpio.spiSetDataMode(0);

// Prepare TX buffer [trigger byte = 0x01] [channel 0 = 0x80 (128)] [placeholder = 0x01]
var sendBuffer = new Buffer([0x01, (8 + 0 << 4), 0x01]); 

// Send TX buffer to SPI MOSI and recieve RX buffer from MISO
var recieveBuffer = rpio.spiTransfer(sendBuffer, sendBuffer.length); 

// Extract value from output buffer. Ignore first byte. 
var junk = recieveBuffer[0],
	MSB = recieveBuffer[1],
	LSB = recieveBuffer[2];

// Ignore first six bits of MSB, bit shift MSB 8 positions and 
// finally add LSB to MSB to get a full 10 bit value
var value = ((MSB & 3) << 8) + LSB; 

console.log('ch' + ((sendBuffer[1] >> 4) - 8), '=', value);

rpio.spiEnd();

@mikaelleven I'm using your code unaltered, and with rpio 0.9.7 installed

got the exactly same error with this script here:

var rpio = require('rpio');

var rxBuffer = rpio.spiTransfer(new Buffer('HELLOSPI'), 8);

for (var i = 0; i <= 7; i++) { 
 process.stdout.write(String.fromCharCode(rxBuffer[i]) + (i == 7 ? '\n' : ' '));
};

looks like the signature of the spiTransfer() has changed. the rxBuffer is now an argument, not a return value
if you look in the file rpio.js , you see that it it needs 3 parameters now .
the following should work

var rpio = require('rpio');

var rxBuffer = newBuffer(8);
rpio.spiTransfer(new Buffer('HELLOSPI'), rxBuffer, 8);

for (var i = 0; i <= 7; i++) {
process.stdout.write(String.fromCharCode(rxBuffer[i]) + (i == 7 ? '\n' : ' '));
};