Skip to content

Instantly share code, notes, and snippets.

@BinRoot BinRoot/rpi.py
Created Sep 23, 2014

Embed
What would you like to do?
Interacting with Raspberry Pi and Thinpot potentiometer
#!/usr/bin/env python
import time
import os
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
DEBUG = 1
# read SPI data from MCP3008 chip, 8 possible adc's (0 thru 7)
def readadc(adcnum, clockpin, mosipin, misopin, cspin):
if ((adcnum > 7) or (adcnum < 0)):
return -1
GPIO.output(cspin, True)
GPIO.output(clockpin, False) # start clock low
GPIO.output(cspin, False) # bring CS low
commandout = adcnum
commandout |= 0x18 # start bit + single-ended bit
commandout <<= 3 # we only need to send 5 bits here
for i in range(5):
if (commandout & 0x80):
GPIO.output(mosipin, True)
else:
GPIO.output(mosipin, False)
commandout <<= 1
GPIO.output(clockpin, True)
GPIO.output(clockpin, False)
adcout = 0
# read in one empty bit, one null bit and 10 ADC bits
for i in range(12):
GPIO.output(clockpin, True)
GPIO.output(clockpin, False)
adcout <<= 1
if (GPIO.input(misopin)):
adcout |= 0x1
GPIO.output(cspin, True)
adcout >>= 1 # first bit is 'null' so drop it
return adcout
# change these as desired - they're the pins connected from the
# SPI port on the ADC to the Cobbler
SPICLK = 18
SPIMISO = 23
SPIMOSI = 24
SPICS = 25
# set up the SPI interface pins
GPIO.setup(SPIMOSI, GPIO.OUT)
GPIO.setup(SPIMISO, GPIO.IN)
GPIO.setup(SPICLK, GPIO.OUT)
GPIO.setup(SPICS, GPIO.OUT)
# 10k trim pot connected to adc #0
potentiometer_adc = 0;
last_read = 0 # this keeps track of the last potentiometer value
tolerance = 5 # to keep from being jittery we'll only change
# volume when the pot has moved more than 5 'counts'
while True:
# we'll assume that the pot didn't move
trim_pot_changed = False
# read the analog pin
trim_pot = readadc(potentiometer_adc, SPICLK, SPIMOSI, SPIMISO, SPICS)
# how much has it changed since the last read?
pot_adjust = abs(trim_pot - last_read)
if ( pot_adjust > tolerance ):
trim_pot_changed = True
print trim_pot
if ( trim_pot_changed ):
set_volume = trim_pot / 10.24 # convert 10bit adc0 (0-1024) trim pot read into 0-100 volume level
set_volume = round(set_volume) # round out decimal value
set_volume = int(set_volume) # cast volume as integer
if DEBUG:
print "set_volume", set_volume
if set_volume > 90:
os.system('aplay sounds/one.wav')
elif set_volume > 80:
os.system('aplay sounds/small.wav')
elif set_volume > 70:
os.system('aplay sounds/step.wav')
elif set_volume > 60:
os.system('aplay sounds/for_man.wav')
elif set_volume > 50:
pass
elif set_volume > 40:
os.system('aplay sounds/one.wav')
elif set_volume > 30:
os.system('aplay sounds/giant.wav')
elif set_volume > 20:
os.system('aplay sounds/leap.wav')
elif set_volume > 10:
os.system('aplay sounds/for_man2.wav')
elif set_volume > 0:
os.system('aplay sounds/kind.wav')
# save the potentiometer reading for the next loop
last_read = trim_pot
# hang out and do nothing for a half second
time.sleep(0.5)
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.