How to use 24Bit data (variable)

[stefan.erni]

Hi Ben

I read from a Ad-Converter a 24bit Value with a SPI Bus in a Byte Array.
I suspect I can not process this in 24 bits so I have to reduce it to a 16 bit value (signed int).

Are there commands similar to make16 () in FC too?


from the data_pdf
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The device provides 24 bits of data in binary twos complement format. The size of one code (LSB) is calculated
using Equation 8.
1 LSB = (2 × VREF / Gain) / 224 = +FS / 223 (8)
A positive full-scale input produces an output code of 7FFFFFh and the negative full-scale input produces an
output code of 800000h. The output clips at these codes for signals exceeding full-scale. Table 9 summarizes the
ideal output codes for different input signals. All 24 bits toggle when the analog input is at positive or negative
full-scale.

[LeighM]

You can get the 16 bit signed value by reading the two most significant bytes from the byte array (MSB,NSB,LSB)

Code: Select all

SINT16 = MSB << 8
SINT16 = SINT16 | NSB