AT28C256-rpi-util/eeprom.py

#!/bin/env python3
from sys import exit
from time import sleep
from RPi.GPIO import IN, OUT
import RPi.GPIO as GPIO
from re import fullmatch
import argparse
import atexit
# 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
#

A = [
     # 27, 22, 10, 9, 11, 5, 6, 13,
        13, 6, 5, 11, 9, 10, 22, 27,  # A0 - A7
        2, 3, 4, 17,  # A8 - A11
        23, 18, 15  # A12 - A14
]

# IO = gpio_r[4:12]  # 8 io pins
# IO.reverse()
IO = [ 24, 25, 8, 7, 12, 16, 20, 21 ]

OEb = 26    # Output Enable
WEb = 19    # Write Enable
CEb = 14     # Chip Enable is hooked up to A15 on the processor

controls = [CEb, WEb, OEb]

# TIMES
# Read:
t_ACC = 150 * 1e-9  # Address to Output Delay

# Write:
t_AS = 0            # Address Setup time
t_AH = 50 * 1e-9    # Address Hold Time
t_CS = 0            # Chip Select Hold Time
t_WP = 100 * 1e-9   # Write Pulse Width
t_DS = 50 * 1e-9    # Data Setup Time_CS = 0
t_DH = 0            # Data Hold Time
t_WPH = 50 * 1e-9   # Write Puls High
# t_WPH = 50 * 1e-4   # Write Pulse High !!!2*e5 longer than in Datasheet, since shorter high caused Problems with my Chip!!!



def setup_address_control_pins():
    # setup the pins
    GPIO.setmode(GPIO.BCM)
    for pin in controls:
        GPIO.setup(pin, OUT, initial=1)  # inverted, is 1 means disable
    for pin in A:
        GPIO.setup(pin, OUT, initial=0)

def setup_io_pins(IOdirection=OUT):
     # OUT when writing and IN when reading
    for pin in IO:
        GPIO.setup(pin, IOdirection)

def cleanup():
    GPIO.cleanup()


def print_pins():
    for i in range(len(A)):
        print(f" A{i:02} - {A[i]}")
    for i in range(len(IO)):
        print(f"IO{i:02} - {IO[i]}")
    print(f" CEb - {CEb}")
    print(f" WEb - {WEb}")
    print(f" OEb - {OEb}")


def set_address(address: int, bits=8):
    """
    set the address pins to the given value
    """
    ad_bin = format(address, f"0{bits}b")  # get the x-bit verion if the address, eg 12 -> 00001100
    for j in range(bits):
        # print("Address:", address, ad_bin, j)
        if ad_bin[bits-1-j] == "0":
            GPIO.output(A[j], 0)
        elif ad_bin[bits-1-j] == "1":
            GPIO.output(A[j], 1)
    return ad_bin


def get_bits(i: int):
    """
    return how many bits are needed to express the number in binary
    """
    return len(bin(i)) - 2  # -2 for the "0x"


def convert_to_int(v):
    """
    convert 0xABC and 0b0101 to int
    """
    if type(v) == str and fullmatch(f"0x[0-9,a-f,A-F]+", v):
        return int(v.replace("0x", ""), 16)
    elif type(v) == str and fullmatch(f"0b[0]+", v):
        return int(v.replace("0b", ""), 2)
    return int(v)


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 erase(from_ad=0, to_ad=32767, **keys):
    """
    Write all 1 to the EEPROM
    WEb controlled
    """
    data = [0xff for i in range(from_ad, to_ad)]
    write(data, from_ad=from_ad, **keys)
    print("Erased EEPROM - Done!")
    return


def write_byte(byte, address, verbose=True): 
    GPIO.output(OEb, 1)
    # setup the address
    ad_bin = set_address(address, bits=15)
    setup_io_pins(OUT) 
    # Setup Data
    for j in range(8):
        if byte[7-j] == "1":
            bit = 1
        else:
            bit = 0
        GPIO.output(IO[j], bit)
    # wait "Address" Setup Time
    sleep(t_AS)
    # wait "Data Setup Time"
    sleep(t_DS)

    GPIO.output(CEb, 0)
    # Start the write pulse -> enable WEb
    GPIO.output(WEb, 0)

    # wait until minimum write pulse width is reached. in theory, should be t_WP-t_DS but this caused problems
    sleep(t_WP)

    # End Write Pulse -> disable WEb
    GPIO.output(WEb, 1)
    GPIO.output(CEb, 1)

    # wait "Data Hold"
    sleep(t_DH)

    GPIO.output(CEb, 0)
    GPIO.cleanup(IO)
    setup_io_pins(IN)

    # check the toggle bit IO6, if it stops toggling the write is done
    timeout = 0
    while timeout < 1e3:
        GPIO.output(OEb, 0)
        sleep(1e-9)
        bit1 = GPIO.input(IO[6])
        GPIO.output(OEb, 1)
        sleep(1e-9)
        GPIO.output(OEb, 0)
        sleep(1e-9)
        bit2 = GPIO.input(IO[6])
        GPIO.output(OEb, 1)
        sleep(1e-9)
        if bit1 == bit2:
            timeout = 1e3
        timeout += 1
    GPIO.output(CEb, 1)
    if verbose:
        print(f"Writing:\t0b{format(address, '015b')} - 0b{byte} ||| 0x{format(address, '04x')} - {hex(int(byte, 2))}")


def read_byte(address):
    GPIO.output(WEb, 1)
    setup_io_pins(IN)
    # set the address valid
    ad_bin = set_address(address, bits=15)

    # low in chip/output enable -> enable
    GPIO.output(CEb, 0)
    GPIO.output(OEb, 0)

    # wait the "Address to Output Delay" until the output is valid
    sleep(t_ACC)

    byte = ""
    for j in range(8):
        if GPIO.input(IO[7-j]) == 1:
            byte += "1"
        else:
            byte += "0"

    # high in OEb and CEb -> disable
    GPIO.output(OEb, 1)
    GPIO.output(CEb, 1)
    return int(byte, 2)


def read(from_ad=0, to_ad=255, delay=1e-3, ignore=[0xff], verbose=True, single_step=False, compare=None):
    """
    from_ad:    start address from where to read
    to_ad:      end address to read to
    delay:      delay between readings in s
    verbose     wether to print the reading
    ignore      list of values which are not printed
    """
    content = []
    unequal = []
    for i in range(from_ad, to_ad + 1):
        byte = read_byte(i)
        content.append(byte)

        if not compare and verbose and not byte in ignore:
            print(f"Reading:\t0b{format(i, '015b')} - 0b{format(byte, '08b')} ||| 0x{format(i, '04x')} - 0x{format(byte, '02x')}")
        elif compare:
            if not compare[i] == byte:
                unequal.append(i)
                print(f"Unequal at Address 0x{format(i, '04x')} ||| File: 0x{format(compare[i], '02x')} vs EEPROM: 0x{format(byte, '02x')}")

        # wait artifical delay
        sleep(delay)
        if single_step:
            input("Press Return to read the next byte")
    if compare:
        return unequal
    return content


def write(content: list, from_ad=0, delay=0, single_step=False, verbose=True, check_written=True):
    """
    Write a list if bytes to the eeprom.
    WEb controlled
    """
    or_content = content.copy()
    content = get_8_bit(content)
    failed = []
    print(f"Writing to EEPROM: {len(content)} bytes from address {hex(from_ad)}.")

    for i in range(len(content)):
        write_byte(content[i], from_ad + i, verbose=verbose)
        # wait artifical delay
        sleep(delay)
        if single_step:
            input("Press Return to write the next byte")
    print("Write to EEPROM - Done!")
    if check_written:
        print("Comparing EEPROM to file...")
        failed = read(from_ad=from_ad, delay=delay, single_step=single_step, verbose=False, compare=or_content)
        while len(failed) > 0:
            for ad in failed:
                write_byte(content[ad], ad, verbose=verbose)
                failed = read(from_ad=from_ad, delay=delay, single_step=single_step, verbose=False, compare=or_content)
        print("Comparing complete")
    return

def get_bytes(filepath, from_ad=0):
    with open(filepath, "rb") as file:
        bindata = []
        for byte in file.read(): 
            bindata.append(byte)
    return bindata[from_ad:]


def main():
    parser = argparse.ArgumentParser(
        prog="AT28C256-EEPROM Writer",
        description="Read and write from/to an AT28C256 EEPROM via the Raspberry Pi 4's GPIO pins\n2023 Matthias Quintern",
        epilog="Numbers can be passed as int, hex prefixed with '0x' and binary prefixed with '0b'",
    )
    parser.add_argument("--write", "-w", dest="write", action="store_true", default=False, help="write binary file onto the EEPROM")
    parser.add_argument("--compare", "-c", dest="compare", action="store_true", default=False, help="compare EEPROM content to binary file")
    parser.add_argument("--read", "-r", dest="read", action="store_true", default=False, help="read the contents of the EEPROM")
    parser.add_argument("--erase", "-e", dest="erase", action="store_true", default=False, help="erase the contents of the EEPROM")
    parser.add_argument("--file", "-f", metavar="file", dest="file", action="store", default="", help="file for --write and --compare")
    parser.add_argument("--from", metavar="start-address", dest="from_ad", action="store", default=0, type=convert_to_int, help="start at address x")
    parser.add_argument("--to", metavar="end-address", dest="to_ad", action="store", default=32767, type=convert_to_int, help="end at address y (inclusive)")
    parser.add_argument("--single-step", dest="single_step", action="store_true", default=False, help="single step the program")
    parser.add_argument("--delay", dest="delay", metavar="delay", action="store", default=0, help="extra delay between cycles")
    parser.add_argument("--ignore", dest="ignore", metavar="numbers", action="store", nargs="*", type=convert_to_int, default=[0x100], help="ignore the numbers a b ... Default=[0xff]")
    parser.add_argument("--verbose", dest="verbose", action="store_true", default=False, help="increase verbosity")
    parser.add_argument("--print-pins", dest="print_pins", action="store_true", default=False, help="print the pin layout and exit")

    args = parser.parse_args()

    if (args.write or args.compare) and not args.file:
        parser.error('--file is required with --write and --compare')

    if args.print_pins:
        print_pins()
        exit(0)
    if args.erase:
        erase(from_ad=args.from_ad, to_ad=args.to_ad, delay=args.delay, single_step=args.single_step, verbose=args.verbose)
    if args.write:
        write(get_bytes(args.file, from_ad=args.from_ad), from_ad=args.from_ad, delay=args.delay, single_step=args.single_step, verbose=args.verbose)
    if args.read:
        read(from_ad=args.from_ad, to_ad=args.to_ad, delay=args.delay, single_step=args.single_step, verbose=args.verbose, ignore=args.ignore)
    if args.compare:
        compare(from_ad=args.from_ad, to_ad=args.to_ad, delay=args.delay, single_step=args.single_step, verbose=args.verbose, ignore=args.ignore, compare=get_bytes(args.file))


if __name__ == '__main__':
    atexit.register(cleanup)
    setup_address_control_pins()
    main()