SD-to-TFT ProMicro

uint8_t readSDToScreen_320x240i(uint32_t fromBlock)
{
  if (!sdCardInitialized) return;

  uint8_t res1 = 0xff;
  uint8_t tries = 0;

  while (res1 == 0xff && tries < 32) {
    SPI_transfer(0xff);
    SDCS_LOW();
    SD_command(18, fromBlock, 0);
    res1 = SD_readRes1();
    if (res1 == 0xff) {
      SPI_transfer(0xff);
      SDCS_HIGH();
      tries++;
    }
  }

  cli();

  if (tries == 32)
  {
    return SD_ERR_CMD18_FAILED;
  }

  asm volatile(
    "ldi    r16,1\n\t"
    "mov    __tmp_reg__,r16\n\t"
    "clr    __zero_reg__\n\t"
    "clr    r22\n\t"
    "clr    r23\n\t"
    "clr    r24\n\t"
    "clr    r25\n\t"
    "clr    r18\n\t"
    "clr    r26\n\t"
    "clr    r27\n\t"
    "ldi    r16, 0xff\n\t"

    // wait for datablock start (0xfe)
  "waitForDBStart:\n\t"
    "in     r17, 0x2d\n\t"
    "in     r17, 0x2e\n\t"
    "out    0x2e, r16\n\t"
  "waitForDBStartResponse:\n\t"
    "in     r17, 0x2d\n\t"
    "sbrs   r17, 7\n\t"
    "rjmp   waitForDBStartResponse\n\t"
    "in     r17, 0x2e\n\t"
    "cpi    r17, 0xfe\n\t"
    "brne   waitForDBStart\n\t"

    // initiate first SPI transfer of data block
    "out    0x2e, r16\n\t"
    "clr    r20\n\t"
    "clr    r21\n\t"

    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through
    "nop\n\t"  // wait for the first byte to come through

  "SPItoScreenLoop:\n\t"
    // Read last byte from SPI
    "in     r17, 0x2e\n\t"
    "push   r17\n\t"
    // initiate next SPI transfer while we output to screen
    "out    0x2e, r16\n\t"

    // PORTF
    "out    0x11, r17\n\t"
    // PORTD
    "out    0x0b, r17\n\t"
    // Toggle ILI WR
    "cbi    0x08, 6\n\t"
    "sbi    0x08, 6\n\t"

    "rjmp   checkDone\n\t"

    "sbrs   r20,0\n\t"
    "rjmp   checkDone\n\t"

    "rjmp   checkDone\n\t"

    "add    r18, __tmp_reg__\n\t"
    "adc    r27, __zero_reg__\n\t"

    "cpi    r18, 0x40\n\t"
    "brne   checkDone\n\t"
    "cpi    r27, 0x01\n\t"
    "brne   checkDone\n\t"

    // next line
    "clr    r18\n\t"
    "clr    r27\n\t"

    "subi   r26, 0xfe\n\t"  // Add 2
    "sbrc   r26, 0\n\t"
    "rjmp   handleField1\n\t"
    "cpi    r26, 0xf0\n\t"  // 240 ? reset to 1
    "brne   sendPASET\n\t"
    "ldi    r26, 1\n\t"
    "rjmp   sendPASET\n\t"
  "handleField1:\n\t"
    "cpi    r26, 0xf1\n\t"
    "brne   sendPASET\n\t"  // 241 ? reset to 0
    "clr    r26\n\t"
  "sendPASET:\n\t"
    // Send PASET command 0x2b
    "ldi    r17, 0x2b\n\t"
    "out    0x11, r17\n\t"
    "out    0x0b, r17\n\t"
    "cbi    0x0e, 6\n\t"
    "cbi    0x08, 6\n\t"
    "sbi    0x08, 6\n\t"
    "sbi    0x0e, 6\n\t"
    // Send zero
    "out    0x11, __zero_reg__\n\t"
    "out    0x0b, __zero_reg__\n\t"
    "cbi    0x08, 6\n\t"
    "sbi    0x08, 6\n\t"
    // Send current row as start address
    "out    0x11, r26\n\t"
    "out    0x0b, r26\n\t"
    "cbi    0x08, 6\n\t"
    "sbi    0x08, 6\n\t"
    // Send zero
    "out    0x11, __zero_reg__\n\t"
    "out    0x0b, __zero_reg__\n\t"
    "cbi    0x08, 6\n\t"
    "sbi    0x08, 6\n\t"
    // Send 0xef as end address
    "out    0x11, r26\n\t"
    "out    0x0b, r26\n\t"
    "cbi    0x08, 6\n\t"
    "sbi    0x08, 6\n\t"

    // Send RAMWR command 0x2c
    "ldi    r17, 0x2c\n\t"
    "out    0x11, r17\n\t"
    "out    0x0b, r17\n\t"
    "cbi    0x0e, 6\n\t"
    "cbi    0x08, 6\n\t"
    "sbi    0x08, 6\n\t"
    "sbi    0x0e, 6\n\t"

  "checkDone:\n\t"
    // Check if we are done
    "add    r20, __tmp_reg__\n\t"
    "adc    r21, __zero_reg__\n\t"
    "cpi    r21,2\n\t" // test against 512
    "brne   jmpToStart\n\t"
    "cpi    r20,0\n\t" // test against 513 as we skip the first write to let us write to screen while waiting for SPI
    "brne   jmpToStart\n\t"

    "rjmp   readCRC\n\t"

  "jmpToStart:\n\t"
    "rjmp   SPItoScreenLoop\n\t"

  "readCRC:\n\t"
    "in     r17, 0x2d\n\t"
    "in     r17, 0x2e\n\t"
    "out    0x2e, r16\n\t"
  "readCRCResponse:\n\t"
    "in     r17, 0x2d\n\t"
    "sbrs   r17, 7\n\t"
    "rjmp   readCRCResponse\n\t"

  "checkLoop:\n\t"
    "add    r22, __tmp_reg__\n\t"
    "adc    r23, __zero_reg__\n\t"
    "adc    r24, __zero_reg__\n\t"
    "cpi    r22, 0xbe\n\t"
    "brne   jumpToDBStart\n\t"
    "cpi    r23, 0xd3\n\t"
    "brne   jumpToDBStart\n\t"
    "cpi    r24, 0x04\n\t"
    "brne   jumpToDBStart\n\t"
    "rjmp   end\n\t"

  "jumpToDBStart:\n\t"
    "rjmp   waitForDBStart\n\t"

  "end:\n\t"
    :
    :
    : "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23", "r24", "r25", "r26", "r27"
  );
  sei();

  SDCS_HIGH();

  SD_CMD12();

  return 0;
}