On 8/19/24 1:47 AM, Alexandru Ardelean wrote: > The AD7606C-16 and AD7606C-18 are pretty similar with the AD7606B. > The main difference between AD7606C-16 & AD7606C-18 is the precision in > bits (16 vs 18). > Because of that, some scales need to be defined for the 18-bit variants, as > they need to be computed against 2**18 (vs 2**16 for the 16 bit-variants). > > Because the AD7606C-16,18 also supports bipolar & differential channels, > for SW-mode, the default range of 10 V or ±10V should be set at probe. > On reset, the default range (in the registers) is set to value 0x3 which > corresponds to '±10 V single-ended range', regardless of bipolar or > differential configuration. > > Aside from the scale/ranges, the AD7606C-16 is similar to the AD7606B. > > And the AD7606C-18 variant offers 18-bit precision. The unfortunate effect > of this 18-bit sample size, is that there is no simple/neat way to get the > samples into a 32-bit array without having to do a home-brewed bit-buffer. > The ADC must read all samples (from all 8 channels) in order to get the > N-th sample (this could be reworked to do up-to-N-th sample for scan-direct). > There doesn't seem to be any quick-trick to be usable to pad the samples > up to at least 24 bits. > Even the optional status-header is 8-bits, which would mean 26-bits of data > per sample. > That means that when using a simple SPI controller (which can usually read > 8 bit multiples) a simple bit-buffer trick is required. > Maybe it would be better to just use .bits_per_word = 18 for the 18-bit ADC and not worry about "simple" SPI controller support for that one?
