How to build the serial number?

[RudolfAtHome]

The file "lgt8xp.h" contains 4 pointers for reading out the serial number. In which order do the values have to be linked with one another?

define GUID0 (((volatile unsigned char )0xF3))

define GUID1 (((volatile unsigned char )0xF4))

define GUID2 (((volatile unsigned char )0xF5))

define GUID3 (((volatile unsigned char )0xF6))

[LaZsolt]

I think no rule how to use it.

uint32_t guid = (uint32_t)&GUID0;
Serial.println(guid, HEX);

uint32_t guid = ((uint32_t)GUID3 << 24) | (GUID2 << 16) | (GUID1 << 8) | GUID0;
Serial.println(guid, HEX);

#define guid (*((volatile uint32_t *)0xF3))
Serial.println(guid, HEX);

[RudolfAtHome]

To Lazolt: This gives very strange / incorrect results, so my question remains open!

uint32_t guid = (uint32_t)&GUID0; Serial.println(guid, HEX); Result: F3 -> wrong, that's an address? uint32_t guid = ((uint32_t)GUID3 << 24) | (GUID2 << 16) | (GUID1 << 8) | GUID0; Serial.println(guid, HEX); Result: FFFFAB8A -> looks not very serious

define guid (((volatile uint32_t )0xF3))

Serial.println(guid, HEX); Result: 6F49AB8A -> another result...

[LaZsolt]

I tested it. I think we run into a compiler bug. If GUID1 bigger than 0x7F then the (unit32_t) shift result upper two bytes will be 0xFFFF. With another words. If an unsigned 8 bit variable which bigger than 0x7F and shifted left by 8, then the result negative 16 bit number. (integer)

[LaZsolt]

Here is the tested GUID printing sketch.

/* GUID test */

uint32_t guid_a, guid_b, guid_c, guid_d;

void setup() {
  Serial.begin(38400);

  guid_a = (*((uint32_t *)&GUID0));
  Serial.println(guid_a, HEX);

  Serial.println((*((uint32_t *)&GUID0)), HEX);

#define guid_b (*((uint32_t *)0xF3))
  Serial.println(guid_b, HEX);

  Serial.println((*((uint32_t *)0xF3)), HEX);

  guid_c = ((uint32_t)GUID3 << 24) | ((uint32_t)GUID2 << 16) | ((uint32_t)GUID1 << 8) | GUID0;
  Serial.println(guid_c, HEX);

  Serial.println();
  Serial.println();
}

void loop() {}

[dwillmore]

@RudolfAtHome does this code work for you? If so, please close this issue.

[RudolfAtHome]

It's solved for me since May 15, 2021