Modern Device Forum

Code: Select all

import time
import spidev

spi_ch = 0

# Enable SPI
spi = spidev.SpiDev(0, spi_ch)
spi.max_speed_hz = 1200000

def read_adc(channel, vref = 3.3):

    if channel > 7 or channel < 0:
        return -1

    # spi.xfer2 sends three bytes and returns three bytes:
    # byte 1: the start bit (always 0x01)
    # byte 2: configure bits, see MCP3008 datasheet table 5-2
    # byte 3: don't care
    r = spi.xfer2([1, 8 + channel << 4, 0])

    # Three bytes are returned; the data (0-1023) is in the
    # lower 3 bits of byte 2, and byte 3 (datasheet figure 6-1)    
    v = ((r[1] & 3) << 8) + r[2]

    return v;

while True:
    for i in range(8):
        value = read_adc(i)
        print "%4d" % value,
    time.sleep(0.2)
    print;