Beckie's ROM Tool

Firmware, shield, and level shifter for reading and programming ROMs using an Arduino Mega.

Hardware Required

• Arduino Mega
• RGB LCD Shield from Adafruit
• Beckie's ROM Tool Arduino Mega Shield
• Beckie's ROM Tool Level Shifter
• 3x Texas Instruments SN74LVCH16T245 for level shifter board
• 1x Texas Instruments SN74LVC2T45 for level shifter board
• A whole bunch of headers for shield and level shifter board

Optional Hardware

• SOP44/Chinese ROM Breakout Board

Software Required

• Arduino IDE
• RGB LCD Shield Library from Adafruit

Provided Functionality

• Change backlight color! Woo!
• Configurable data bus width (8 or 16, little- or big-endian)
• Configurable address bus width (8 to 31, in half-line increments)
• Configurable delay between reads or writes (0 to 10000 microseconds)
• Raw binary or hexadecimal input and output over serial
• Inspect individual words of the ROM on the LCD
• Inspect 8 (in 8-bit mode) or 4 (in 16-bit mode) words at once on the LCD
• Dump ROM over serial
• Program ROM over serial
• Binary counter mode using address bus
• Logic probe mode using data bus
• Self test mode (connect A0-A15 or A30-A15 to Q0-Q15, respectively, to test address and data lines)
• LCD character chart 'cause why not
• Party mode!
• Save and load settings using the Arduino's EEPROM
• 5V logic using the shield, 3.3V logic using the shield + level shifter
• Serial command line interface; connect and enter the command ? to get a list of further commands

Dumping or Programming a ROM

This is easiest to do with the provided scripts rtdownload.py and rtupload.py. These will connect to the ROM Tool over serial, configure it, start the dumping or programming process, and save the output or read the input from a file. (The pySerial library is required; refer to the pySerial installation instructions for details.)

Dump a ROM to the file rom.bin with this command:

$ tools/rtdownload.py -u /dev/tty.usbmodemfa131 -d 8 -a 16 -y 0 -f raw -o rom.bin

Program a ROM with the contents of the file rom.bin with this command:

$ tools/rtupload.py -u /dev/tty.usbmodemfa131 -d 8 -a 16 -y 0 -f raw -i rom.bin

Provide the path to the device with -u, the data width with -d (8, 16le, or 16be), the address width with -a (8, 8.5, ..., 31), the delay between reads or writes with -y (0 through 10000), the format with -f (raw or hex), the output file with -o, and the input file with -i.

If you are having difficulty dumping a ROM reliably, you can attempt several dumps and compare them using the erdrcr tool from goodiebin. With enough dumps you may be able to construct an error-corrected version.

This command will compare three dumps, 1.bin, 2.bin, and 3.bin, and output an error-corrected version to 4.bin:

$ erdrcr 1.bin 2.bin 3.bin -o 4.bin
Address.Mask	0's	1's	Correction
00000015.02:	2	1	0
0000001C.08:	1	2	1
2 out of 320 bits mismatched (0.625% error rate)
all errors correctable

If you wish to talk to the ROM Tool directly over its serial interface, you can do so using the miniterm utility that comes with pySerial. Make sure to specify --rtscts, --echo, --eol LF, and a baud rate of 250000:

$ python -m serial.tools.miniterm --rtscts --echo --eol LF /dev/tty.usbmodemfd121 250000
--- Miniterm on /dev/tty.usbmodemfd121  250000,8,N,1 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
?
Beckie's ROM Tool Serial Interface
![<string>]         Echo string over serial
b[<color>]          Report or set backlight color (0, 1, ..., 7)
d[<width>]          Report or set data width (8, 16 LE, 16 BE)
a[<width>]          Report or set address width (8, 8.5, ..., 31)
y[<delay>]          Report or set I/O delay in microseconds (0 - 10000)
f[<format>]         Report or set I/O format for D and P (Raw, Hex)
i[<addr>[ <addr>]]  Print hex dump of specified range of ROM
w<addr>[ <data>]    Program ROM using plain address and hex data
S<rest-of-record>   Program ROM using Motorola SREC record
:<rest-of-record>   Program ROM using Intel HEX record
%<rest-of-record>   Program ROM using Tektronix extended HEX record
M                   Report maximum address (inclusive) in hex
D[<addr>[ <addr>]]  Start dumping specified range or entire ROM over serial
P[<addr>[ <addr>]]  Start programming specified range or entire ROM over serial
s<slot>             Save settings to Arduino EEPROM (0, 1, ..., F)
r<slot>             Load settings from Arduino EEPROM (0, 1, ..., F)
A<addr>             Set value on address bus (binary counter)
Q                   Print value on data bus (logic probe)
c, cs, ch           Clear LCD, show cursor, hide cursor
c[<column> ]<row>   Set LCD cursor position
p[<string>]         Print string on LCD
m                   Return to menu display
d16le
OK
a25
OK
i 600 63f
00000600: 6863 736B 6D75 333A 4334 4236 4444 2034 6576 3A72 7522 6E27 5053 4920 4544 6556  chksum:34C6BDD4 ver:"u'nSP IDEVe
00000610: 2072 2E31 2E36 2232 7520 6573 3A72 7322 6E75 6C70 7375 2022 6F62 7964 223A 5053  r 1.6.2" user:"sunplus" body:"SP
00000620: 3247 3334 0022 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000  G243"...........................
00000630: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000  ................................

Notice: The i and w commands use word offsets while the S, :, and % commands use byte offsets. If you are working with a 16-bit ROM, addresses passed to or returned by the i and w commands will be half the equivalent address passed to the S, :, and % commands.