@tomero Those two code fragments are equivalent, it doesn't change the calculation. And as far as we can see the code works fine. If you still do not think so, can you tell us what you expect, what you get, and why you think it is the wrong answer?


Yes as you say that code is equivalent, and I ...

Hi all, thank you for your response.

I have solution by modification the formula of 2's complement:
To
But im still confused, why its return different but in same purpose.

I try write some code to calculate some bytes, but the result is invalid, result should be "0x28". Please help.

void setup() {
Serial.begin(115200);

uint8_t data[] = {0x13, 0x00, 0x93, 0x00, 0x64, 0x09, 0xC4, 0x01, 0x7E, 0x8B, 0x01, 0x06, 0x00, 0x08, 0xE0, 0x02, 0x8E, 0x25, 0x00, 0x00, 0x00 ...