GameBoy Serial Reader

Introduction

This tool used RS232C serial interface. it can connect to PC-compatible and Macintosh, UNIX.

Schematic Structure

this is easy structure, 40pin PIC micro computer and RS232C interface, voltage regulator.

Schematic Diagram




How to make

take it easy, no problem.

PCB Art work




How to use

please connect cable to PC via modem-cable. and GB-Reader requires AC-Adapter(center GND, outside +12 volt)

please access to GB-Reader with 115.2Kbps 8bit 1stopbit parity-none in any terminal software.

GB-Reader returns prompt of "gbr>" if communication successfull. LED on the GB-Reader is linked with RESET signal on cartridge. you can remove cartridge safty in LED is black. you can use command in the command prompt.

  [ESC]		turn off cartridge power(into removable mode).


  h		display help.


  i		print information in cartridge.


  ir            refresh information from cartridge.(Ver1.0b or later)


  br, bs 	change bank register in ROM/SRAM.

    change bank register in ROM/SRAM.

    [ex.]
      gbr> br 1e	... ROM bank change to 0x1e
      gbr> bs a		... SRAM bank change to 0x0a


  us, ds	up/download backup SRAM

      up/download backup SRAM.
    transfer time is 2 seconds at the 8KB SRAM. if push ESC key is proccess abort.


  dl		download ROM

      download ROM data. typical transfer time is about 64 seconds at 512KB
    if push down ESC key will be abort current proccess.

    [ex.]
      gbr> dl 1000 1fff		... download by UUENCODE
                                    to 0x1fff from 0x1000
      gbr> dl			... download all


  rd	read memory

      read out memory in cartridge.

    [ex.]
      gbr> rd a000		... read out address of 0xa000.
      55


  wd	write memory

      write in memory in cartridge.

    [ex.]
      gbr> wd 0 a		... write value of 0x0a to address 0x0000.


  dm	dump memory

      dump value in memory. ESC key effective.

    [ex.]
      gbr> dm			... dump memory 128bytes from current
                                    adddress.
      gbr> dm 4000		... dump memory 128bytes from address 0x4000
      gbr> dm 4000 4fff		... dump memory to 0x4fff from 0x4000


  cs, cr     calculate checksum

      calculate checksum in current cartridge.
    please compare value from value in () printed by 'i' command. 

    [ex.]
      gbr> cr			... calculate checksum for ROM
      gbr> cs			... calculate checksum for SRAM
      gbr> cr 4000 4fff		... calculate checksum 0x4000 - 0x4fff

program for PIC

• Version 1.0C

reference

• PIC16/17 Microcontroller Data Book/Microchip Technology Inc. 1996/1997
• Errata Sheet for Rev. A PIC16C74 Silicon/Microchip Technology Inc. 1996

sample data

Memory Access timing in Gameboy

• Snapshot of LogicAnalyzing
  
• Logic timing diagram

the access is syncronized with signal of CLK 1.078MHz. RD signal is lo-level in normaly, when write operation, change to hi-level. MREQ is lo-level when access to SRAM.

Sample Schematic of MBC1, MBC2 type cartridges

MBC1 schematic
MBC2 schematic

terminal snapshots

transfer time is 64 seconds at 512K

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