TM4C123: ROM boot loader unexpected response using I2C

#define TIVA_DEVICEADDRESS (0x42<<1)

uint8 status_cmd = COMMAND_GET_STATUS;
uint8 ping_cmd = COMMAND_PING;

void EeSetStart(void)
{
  volatile uint16 x;

  // Start condition
  ACCESS2_CTRL_REG &= ~(EN_ACCESS_BUS);
  x++; // 624 ns
  ACCESS2_CTRL_REG |= (SCL_VAL | SDA_VAL);
  BusyWait1();

  ACCESS2_CTRL_REG &= ~(SDA_VAL);
  BusyWait1();

  ACCESS2_CTRL_REG &= ~(SCL_VAL);
  BusyWait1();
}

void EeSetStop(void)
{
  // stop condition
  ACCESS2_CTRL_REG &= ~(EN_ACCESS_BUS);
  ACCESS2_CTRL_REG &= ~(SCL_VAL | SDA_VAL);
  BusyWait1();

  ACCESS2_CTRL_REG |= SCL_VAL;
  BusyWait1();

  ACCESS2_CTRL_REG |= SDA_VAL;
  BusyWait1();
}

void EeSendByte(BYTE a)
{
  volatile WORD n;
  ACCESS2_CTRL_REG |= EN_ACCESS_BUS;  // automatic control SDA/SCL-VAL
  n++; // this is neccesssary to delay following events

  ACCESS2_CLEAR_INT_REG = 0;

  ACCESS2_IN_OUT_REG=a;
  // Wait until transmission is done
  while (!(ACCESS2_CTRL_REG & ACCESSx_INT)) ;
  ACCESS2_CLEAR_INT_REG = 0;
}

BYTE ReadByte_Ack(UByte nextNoAck)
{
  volatile uint16 Read = 0;

  ACCESS2_CTRL_REG &= ~ACKn;
  while (!(ACCESS2_CTRL_REG & ACCESSx_INT));
  Read=ACCESS2_IN_OUT_REG;   // Read received byte
  ACCESS2_CLEAR_INT_REG = 0;
  if (nextNoAck)
  {
    ACCESS2_CTRL_REG |= ACKn; // don't transmit Acknowledge
  }
  return(Read);
}

BYTE ReadByte_NoAck(void)
{
  volatile uint16 Read = 0;

  ACCESS2_CTRL_REG |= ACKn;  // don't transmit Acknowledge
  while (!(ACCESS2_CTRL_REG & ACCESSx_INT));
  Read=ACCESS2_IN_OUT_REG;   // Read received byte
  ACCESS2_CLEAR_INT_REG = 0;

  return(Read);
}

uint8 send_packet(uint8* data, uint8 size)
{
  uint8 i, ack, checksum = 0;
  for (i = 0; i < size; i++) {
    checksum += data[i];
  }

  do
  {
    EeSetStop();
    EeSetStart();
    EeSendByte(TIVA_DEVICEADDRESS);
  } while (ACCESS2_CTRL_REG & ACKn);

  EeSetStop();
  EeSetStart();

  EeSendByte(size +2);
  EeSendByte(checksum);

  for (i = 0; i < size; i++) {
    EeSendByte(data[i]);
  }

  EeSetStart();
  // Set Device address for read
  EeSendByte(TIVA_DEVICEADDRESS|0x01);

  ack = ReadByte_NoAck();
  debugf("-%02X-\n", ack);
  EeSetStop();

  return ack;
}

uint8 get_packet(uint8* data, uint8* size)
{
  uint8 i, psize, pchecksum, checksum = 0;

  do
  {
    EeSetStop();
    EeSetStart();
    EeSendByte(TIVA_DEVICEADDRESS);
  } while (ACCESS2_CTRL_REG & ACKn);

  EeSetStart();
  EeSendByte(TIVA_DEVICEADDRESS|0x01);
  psize = ReadByte_Ack(0);
  debugf("psize = %02X\n", psize);
  if (psize < *size) *size = psize;
  pchecksum = ReadByte_Ack(0);
  debugf("pchecksum = %02X\n", pchecksum);

  for (i = 0; i < *size; i++) {
    if (i == (*size-1)) {
      data[i] = ReadByte_NoAck();
    } else if (i == (*size-2)) {
      ReadByte_Ack(1);
    } else {
      data[i] = ReadByte_Ack(0);
    }
  }
  for (i = 0; i < *size; i++) {
    checksum = data[i];
  }

  EeSetStart();
  // Set Device address for write
  EeSendByte(TIVA_DEVICEADDRESS);
  if (checksum == pchecksum) {
    EeSendByte(COMMAND_ACK);
    EeSetStop();
    return COMMAND_ACK;
  } else {
    EeSendByte(COMMAND_NAK);
    EeSetStop();
    return COMMAND_NAK;
  }
}

uint8 send_command(uint8* cmd, uint8 size)
{
  uint8 ret;

  uint8 status, ssize;
  ret = send_packet(cmd, size);
  ret = send_packet(&status_cmd, 1);
  ssize = sizeof(status);
  ret = get_packet(&status, &ssize);
  debugf("status: %02X\n", status);
  return ret;
}

void tiva_main()
{
  send_commnad(&ping_cmd, 1);
}

-c2-			<-- expected 0xCC = COMMAND_ACK
-c2-			<-- expected 0xCC = COMMAND_ACK
psize = c2		<-- expected 1
pchecksum = f0		<-- expected 0x40
status: fc		<-- expected 0x40 = COMMAND_RET_SUCCESS