AT28C256-rpi-util/eeprom_sim.py

from time import time

from sys import argv
from time import sleep
from RPi.GPIO import IN, OUT
import RPi.GPIO as GPIO

from opcodes import opcodes_d
# EEPROM AT28C256 Pin names and RPi GPIO Pin Numbers
# b means bar = inverted


gpio_l = [2, 3, 4, 17, 27, 22, 10, 9, 11, 5, 6, 13, 19, 26]
gpio_r = [14, 15, 18, 23, 24, 25, 8, 7, 12, 16, 20, 21]
#
# Defining which 6502 pin goes to which GPIO pin
#
"""
IO = gpio_r[-8:]  # 8 io pins
IO.reverse()
A = [13, 6, 5, 11, 9, 10, 22, 27,
     17, 4, 3, 2, 
     23, 18, 15] 

# OEb = 26    # Output Enable
RWb = 19    # Write Enable
CEb = 14     # Chip Enable is hooked up to A15 on the processor
PHI2 = 26
controls = [CEb, RWb, PHI2]
"""
A = [
    27, 22, 10, 9, 11, 5, 6, 13,  # A0-A7
    4, 2, 18, 3,  # A8-A11
    23, 17, 15   # A12-A14
]

IO = [ 24, 25, 8, 7, 12, 16, 20, 21 ]

RWb = 19    # Write Enable
CEb = 14     # Chip Enable is hooked up to A15 on the processor
PHI2 = 26
controls = [CEb, RWb, PHI2]


# Address setup time
t_AS = 300e-9
# setup the pins
GPIO.setmode(GPIO.BCM)
for pin in controls:
    GPIO.setup(pin, IN)
for pin in A:
    GPIO.setup(pin, IN)

def setup_pins(IOdirection=OUT):
     # OUT when writing and IN when reading
    for pin in IO:
        if IOdirection == OUT:
            GPIO.setup(pin, IOdirection, initial=0)
        elif IOdirection == IN:
            GPIO.setup(pin, IOdirection)
    # print("setup pins", IOdirection)

def print_pins():
    for i in range(len(A)):
        print(f"A{i} - {A[i]}")
    for i in range(len(IO)):
        print(f"IO{i} - {IO[i]}")
    print(f"CEb - {CEb}")
    print(f"RWb - {RWb}")
    print(f"PHI2 - {PHI2}")

def get_8_bit(l: list):
    for i in range(len(l)):
        l[i] =  format(l[i], f"08b")  # get the 8-bit bin value
    return l

def check_enable():
    # assumes the EEPROM is only hooked up via CE. If CE is low, it will ouput data
    if GPIO.input(CEb) == 0 and GPIO.input(RWb) == 1:
        return True
    return False

def decode_address():
    ad_s = ""
    for i in range(len(A)):
        ad_s += str(GPIO.input(A[len(A)-1-i]))
    return int(ad_s, 2)

def simulate(path, verbose=True):
    with open(path, "rb") as file:
        bindata = file.read()
    data = []
    for i in range(len(bindata)):
        data.append(format(bindata[i], "08b"))
    while True:
        GPIO.cleanup(IO)
        setup_pins(IN)
        # address is set on falling edge
        channel = GPIO.wait_for_edge(PHI2, GPIO.FALLING, timeout=1000)  # allow for KeyboardInterrupts
        if channel is None:
            continue
        # wait an address setup time, dependant on clock speed!
        sleep(t_AS)

        enable = check_enable()
        address = decode_address()

        # put the data on the bus
        if enable:
            setup_pins(OUT)
            for i in range(8):
                if data[address][i] == "0":
                    GPIO.output(IO[7-i], 0)
                else:
                    GPIO.output(IO[7-i], 1)
            # wait the output hold time
            if verbose:
                print(f"OUT|||{format(address + 0x8000, '015b')} - {data[address]}|||{format(address + 0x8000, '04x')} - {format(int(data[address], 2), '02x')}", end="")
                if int(data[address], 2) in opcodes_d:
                    print(f" ||| {opcodes_d[int(data[address], 2)]}")
                else:
                    print("")
        elif verbose:
            data_in = ""
            for i in range(8):
                data_in += str(GPIO.input(IO[7-i]))
            print(f"IN |||{format(address, '016b')} - {data_in}|||{format(address, '04x')} - {format(int(data_in, 2), '02x')}")
if len(argv) > 1:
    try:
        simulate(argv[1])
    except KeyboardInterrupt:
        GPIO.cleanup()
else:
    print("No filepath given. Printing Pin-Settings")
    print_pins()
# if performing action from this script, put the code HERE:

GPIO.cleanup()