Demonstrating how to run an eBay AD9850 DDS Module on the RPi GPIO

AD9850.py

#!/usr/local/bin/python
# Run an eBay AD9850 on the RPi GPIO
#
# translated from nr8o's Arduino sketch
# at http://nr8o.dhlpilotcentral.com/?p=83
# 
# m0xpd
# shack.nasties 'at Gee Male dot com'
import RPi.GPIO as GPIO
# setup GPIO options...
GPIO.setmode(GPIO.BOARD)
GPIO.setwarnings(False)

W_CLK = 12              			# Define GPIO pins
FQ_UD = 16
DATA = 18
RESET = 22  

def pulseHigh(pin):               		# Function to send a pulse
	GPIO.output(pin, True)          	# do it a few times to increase pulse width
	GPIO.output(pin, True)          	# (easier than writing a delay loop!)
	GPIO.output(pin, True)
	GPIO.output(pin, False)         	# end of the pulse
	return

def tfr_byte(data):               		# Function to send a byte by serial "bit-banging"
	for i in range (0,8):
		GPIO.output(DATA, data & 0x01)	# Mask out LSB and put on GPIO pin "DATA"
		pulseHigh(W_CLK)              	# pulse the clock line
		data=data>>1                  	# Rotate right to get next bit
	return

def sendFrequency(frequency):     		# Function to send frequency (assumes 125MHz xtal)
	freq=long(frequency*4294967296/125000000)
	for b in range (0,4):
		tfr_byte(freq & 0xFF)
		freq=freq>>8
	tfr_byte(0x00)
	pulseHigh(FQ_UD)
	return

GPIO.setup(W_CLK, GPIO.OUT)       		# setup IO bits...
GPIO.setup(FQ_UD, GPIO.OUT)       		#
GPIO.setup(DATA, GPIO.OUT)        		#
GPIO.setup(RESET, GPIO.OUT)       		#

GPIO.output(W_CLK, False)         		# initialize everything to zero...
GPIO.output(FQ_UD, False)
GPIO.output(DATA, False)
GPIO.output(RESET, False)

pulseHigh(RESET)                  		# start-up sequence...
pulseHigh(W_CLK)
pulseHigh(FQ_UD)

frequency = 7000000               		# choose frequency and
sendFrequency(frequency)          		# start the oscillator