parallel memory dumping using Raspberry Pi GPIO, for AT27C080 8Mbit CMOS EPROM

parallel-eprom-dump.py

#!/usr/bin/python

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BOARD)

# Data and address pins
# MSB first

           # G23 G24 G10 G09 G25 G11 G08 G07  # BCM
           #        MOSI MISO    SCK CE0 CE1  # alt functions
data_pins = [16, 18, 19, 21, 22, 23, 24, 26]  # board
           # O7  O6  O5  O4  O3  O2  O1  O0   # chip
           # 21  20  19  18  17  15  14  13   # AT27C080

assert len(data_pins) == 8, "must have exacty 8 data pins (8 bits/byte)"

             # G19 G16 G26 G20 G21   # BCM
             #                       # alt functions
address_pins = [35, 36, 37, 38, 40]  # board
             #  A4  A3  A2  A1  A0   # chip
             #   8   9  10  11  12   # AT27C080

GPIO.setup(data_pins, GPIO.IN)
GPIO.setup(address_pins, GPIO.OUT, initial=GPIO.LOW)

def read_byte():
	byte = 0
	for i in range(len(data_pins)):
		bit = GPIO.input(data_pins[i])
		byte |= bit * 2**(len(data_pins)-1-i)
		#print i,bit,data_pins[i]
	return byte

def set_address(address):
	assert address < 2**len(address_pins), "attempted to set address %.2x beyond %d address pins" % (address, len(address_pins))
	for i in range(len(address_pins)):
		bit = (address & 2**(len(address_pins)-1-i)) != 0
		GPIO.output(address_pins[i], bit)
		#print i,bit,address_pins[i]

for address in range(0, 2**len(address_pins)):
	set_address(address)
	if address % 4 == 0: print
	print "%.4x =" % (address,),
	#time.sleep(0.5)
	#byte = read_byte()
	#print "%.4x = %.2x" % (address, byte)
	time.sleep(0.2)
	seen = {}
	for i in range(20):
		byte = read_byte()
		if not seen.has_key(byte): seen[byte] = 0
		seen[byte] += 1
		print "%.2x " % (byte,),
		time.sleep(0.1)
	print "  ",
	for saw in sorted(seen.keys()):
		print (str(seen[saw]) + "x") + "%.2x=%s " % (saw, bin(saw)[2:]),
	print
	time.sleep(0.2)