ADS1256 cannot get correct readout value

[victorll998]

I ran the sample code using raspberry pi 4b but I cannot any reading that makes sense to me.

I modified the ads function to get spi buffer readings. It showed that the voltage reading of the built-in pot on channel 0 is always 0 (I double-checked the jumpers and wire connection and they should be fine).

Setting aside the hardware issues, I had a close look at BCM ads library. There is one thing I wasn't sure about. In line 248, why we need a filter for the spi buffer readings? shouldn't it be like " read |= 0xFF000000" as for a sign extension from 24-bit to 32-bit signed integer?