I'm reading data from a device that returns a lot of bytes. 5 bytes are representing a big number that I need. For example, I receive 24C9A75A2E and it means the value is 158002010670. These bytes are in a byte array positions 5 to 9. I tried converting this number to a long like this: long long …

[image] alto777: didn't work here, I'll try again later. That did not work until I made dataRx unsigned. What Arduino board are you running this on? OK, I ran it on the ESP32 - could it be... yes, argh! I can break your code that works by making dataRx signed. So, do we have: UNO char is …

[image] alto777: Learn something every day. The lesson to be learned? Always use int8_t, uint8_t, etc. Then you'll know signed / unsigned. Use char only for ASCII characters. Those are <= 127 so signed / unsigned doesn't matter.

Hey great to see you, I thought we had lost you! You did that fast /10 thread years ago, right?

[image] AKnuts: 46 90 167 201 36 If one were to make a union with one unsigned long long // ULL for short and an 8 byte array the array order can be checked by setting the union as 0x0123456789ABCDEF and then reading the bytes as HEX. When that is known, the order to set the bytes to get a …

[image] alto777: are those bytes in positions 9 to 5? I'm sorry to have asked that question, but without seeing the OP's code I had to, or thought I did. There is nothing that needs any tricks to see that shifting bytes into an integer in all the ways we did should have worked fine. Endianne…

That's why to map the union bytes in Post 22 by setting the 32 bit ULL in a hex pattern and reading the same union bytes as hex. Swaps show up.

[image] GoForSmoke: ...the union... Nope. C++ type punning rules make that undefined behaviour. memcpy or bitwise operations are the correct choice.

[image] Coding_Badly: [image] GoForSmoke: ...the union... Nope. C++ type punning rules make that undefined behaviour. memcpy or bitwise operations are the correct choice. I believe one of the few allowed exceptions to the strict aliasing rules lets you to use a byte pointer to access a…

Hey great to see you, I thought we had lost you! You did that fast /10 thread years ago, right? Sometimes I get a mail from the system and I have a look at the forum, and PM's. Spend my (Arduino) time mostly on maintaining libraries and creating new ones. See - RobTillaart (Rob Tillaart) · GitHu…

Converting a 5-byte big number to a number?

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Converting a 5-byte big number to a number?

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