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Converting 16-bit, little-endian, 2's complement integer to regular integer

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Ben
Ben on 12 Jun 2015
Commented: Walter Roberson on 14 Jun 2015
I'm trying to get various data sets (accelerometer, gyroscope etc.) from a AHRS (a CHR-UM6) and I'm having trouble getting the values out in the correct form. The data received (for each value) is a two row column vector such as:
247
255
These numbers are 16-bit, little-endian, 2's complement and I need to get the actual value. I hope someone can help!
Thanks, Ben

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Accepted Answer

Walter Roberson
Walter Roberson on 12 Jun 2015
swapbytes(typecast(TheByteVector, 'int16'))
TheByteVector should be uint8.

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Ben
Ben on 13 Jun 2015
At first I didn't think this was going to work as swapbytes just seems to switch between little and big endian and I was worried about the two's complement part, but I was pleasantly surprised when my output values were what they should've been, thanks. My code is as follows, for reference:
gyro_x = double(swapbytes(typecast((uint8(packet.data(1:2))),'int16')))*0.0610352;
This is used multiple times for different values. The input packet.data is a double. If there's a cleaner/quicker/more efficient way to do what I'm doing, please share, thanks.
Walter Roberson
Walter Roberson on 14 Jun 2015
gyro_x = double(typecast(uint8(packet.data([2 1]),'int16')) * 0.0610352;
No need to call swapbytes if you don't need to ;-)

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