Encoding of lux and uv in LoRaWAN template seems wrong

[avbentem]

I assume the following code is expected to nicely yield 3 bytes that can be decoded using some simple shifting (like decoded = bytes[0] | bytes[1]<<8 | bytes[2]<<16 rather than some weird bytes[0] + 255 * (bytes[1] | bytes[2]<<8)):

message.addUint8(lux % 255);
message.addUint16(lux / 255);

However, when using modulo and division to get the LSB and MSBs, one should use 256 (or 0x100), not 255. Like 0x123456 % 255 yields the unexpected 0x9C, not 0x56. And 0x123456 / 255 yields 0x1246, not 0x1234.

Using 256 in the calculations fixes that. Other options would be:

message.addUint8(lux);
message.addUint16(lux >> 8);

...or:

message.addUint8(lux);
message.addUint8(lux >> 8);
message.addUint8(lux >> 16);

Note that https://github.com/sensebox/board-support-watterott-fork/tree/master/arduino/samd/libraries/LoraMessage also uses shifting for writeUint16, so encodes 0x1234 into the bytes 0x34 and 0x12 as expected.

But of course, please ensure that my assumption of your intentions is valid!

[avbentem]

I still feel that this is a bug... If you disagree, then please let me know so I can delete the pull request/branch.