last week, I learnt how to read values from I2C for registers which It returns 1 byte of information (0-128) but now, reading again the technical documentation, I read this fact:
“the measurements provided in the form of signed short integers (16 bits or two bytes).”
In the example I sum both values from byte 1 and byte 2, but maybe it is not the right operation.
So, how to show a integer in the register 0x43, 66 with the block I2C Read 8 Bytes?
If I get the first byte and the second one, how to show the right signed short integer?
Each byte should be 8 bits (0-255). If a 16-bit integer is stored/transferred using two bytes, then to “unpack” the 2 x 8 bits into 16 bits, you would do something like:
value = (byte_low | (byte_high << 8))
I don’t know if the EV3 software allows you to use bitwise math. It’s probably easier to do something like:
value = (byte_low + (byte_high * 256))
If value needs to end up being a 16-bit signed value (as opposed to unsigned), then in C you could type cast it to a int16_t, but in EV3 software you would probably need to do something like:
if value > 32767
value = value - 65536
Which byte is high and which is low is dependent on the device you’re trying to read from. The device datasheet should tell you how the registers are configured.
