arduino mega eeprom read/write

mega_reader.ino

/*
D = address 16..23
C = address 8..15
A = address 0..7
L = data 0..7
B0 = !OE
B1 = !WE
B2 = !CE
*/

constexpr uint8_t OE = 1;
constexpr uint8_t WE = 2;
constexpr uint8_t CE = 4;

constexpr int blocksize = 128;

void setaddr(uint32_t addr)
{
  PORTD = (addr>>16)&0x0f;
  PORTC = (addr>>8)&0xff;
  PORTA = addr&0xff;
}

uint8_t readcurrentbyte()
{
  uint8_t data;
  DDRL=0x00;
  PORTB&=~(OE|CE);
  // exact nops required depends on speed class of memory
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  data=PINL;
  PORTB|=(OE|WE|CE);
  return data;
}

void writecurrentbyte(uint8_t data)
{
  DDRL=0xFF;
  PORTL=data;
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  PORTB&=~(WE|CE);
  __asm__ __volatile__("nop\n\t"); // minimum WE/CE pulse time
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  PORTB|=(OE|WE|CE);
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  __asm__ __volatile__("nop\n\t");
  DDRL=0x00;
}

void blindwrite(uint32_t addr, uint8_t data)
{
  setaddr(addr);
  writecurrentbyte(data);
}

void write(uint32_t addr, uint8_t data)
{
  blindwrite(addr,data);
  while(readcurrentbyte() != data){}
}

void writepage(uint32_t addr, uint8_t data[blocksize])
{
  for (uint8_t i = 0; i<blocksize; i++)
  {
    setaddr(addr+i);
    writecurrentbyte(data[i]);
  }
  while(readcurrentbyte() != data[blocksize-1]){}
}


uint8_t read(uint32_t addr)
{
  uint8_t data;
  setaddr(addr);
  return readcurrentbyte();
  
}

void print_block(uint32_t addr, uint32_t len)
{
  for (uint32_t i = 0; i<len; i++)
  {
    if (i%32 == 0 && i != 0) Serial.println("");
    uint8_t data = read(addr+i);
    if (data<0x10) {Serial.print("0");}
    Serial.print(data,HEX);
  }
  Serial.println("");
}

void setup() {
  PORTB|=(OE|WE|CE);
  DDRB|=(OE|WE|CE);

  DDRC=0xFF;
  DDRA=0xFF;
  DDRD=0x0F;
  setaddr(0);
  
  Serial.begin(115200);
  Serial.println("ready");
}

void loop() {
  if (Serial.available() > 0) { //Loop until there's something in the serial buffer
    int cmd = Serial.read();
    switch (cmd)
    {
      case 'w':
        {
          while (Serial.available() < 3) {}
          // read 24b start addr and 8b data
          uint32_t addr = Serial.read();
          addr = addr << 8;
          addr += Serial.read();
          addr = addr << 8;
          addr += Serial.read();
          uint8_t data = Serial.read();
          write(addr,data);
          // print "done"
          Serial.println("done");
        }
        return;
      case 'W':
        {
          while (Serial.available() < 3) {}
          // read 24b start addr and (blocksize)x8b data
          uint32_t addr = Serial.read();
          addr = addr << 8;
          addr += Serial.read();
          addr = addr << 8;
          addr += Serial.read();
          uint8_t data[blocksize];
          Serial.readBytes(data,blocksize);
          writepage(addr,data);
          print_block(addr, blocksize);
          // print "done"
          Serial.println("done");
        }
        return;
      case 'p':
        // dump memory card pages
        {
          uint8_t page = Serial.read();
          blindwrite(0x000A,page);
          // delay a bit in case something needs to slowly page...
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          __asm__ __volatile__("nop\n\t");
          print_block(0, 0x20000);
          // print "done"
          Serial.println("done");
          return;
        }
      case 'd':
        {
          print_block(0, 0x20000);
          // print "done"
          Serial.println("done");
          return;
        }        
      case 'r':
        {
          while (Serial.available() < 4) {}
          // read 24b start addr and 16b length, then dump hex...
          uint32_t addr = Serial.read();
          addr = addr << 8;
          addr += Serial.read();
          addr = addr << 8;
          addr += Serial.read();
          uint16_t len = Serial.read();
          len = len << 8;
          len += Serial.read();
          print_block(addr, len);
          // print "done"
          Serial.println("done");
          return;
        }
      case 't':
        {
          
          return;
        }
    }
  }
}

writetest.ps1

$data = Get-Content -Path "D:\Projects\atariportfolio\XROM.bin" -Encoding Byte

$port= new-Object System.IO.Ports.SerialPort COM8,115200,None,8,one

$port.open()
$port.ReadLine()

for ($i=0; $i -lt $data.Length; $i+=128) {
  #write a block
  $port.Write([char]'W')
  $port.Write([byte[]]((($i -shr 16) -band 0xff),(($i -shr 8) -band 0xff),($i -band 0xff)),0,3)
  $datalen = $data.Length - $i
  if ($datalen -lt 128)
  {
    $port.Write($data,$i,$datalen)
    $port.Write([byte[]](, 0 * 100),0,(128 - $datalen))
  }
  else
  {
    $port.Write($data,$i,128)
  }
  # 4 lines data readback
  $port.ReadLine()
  $port.ReadLine()
  $port.ReadLine()
  $port.ReadLine()

  # "done"
  $port.ReadLine()
  start-sleep -m 10
}
$port.Write([char]'d')
do {
  $dumpline = $port.ReadLine()
  $dumpline
} while ($dumpline -notlike "*done*")

$port.Close()