hi everyone, as I posted in an other thread, the new proto boards have arrived…after assembling everything, beside button reading (done by a 74hc165) where I have forgotten an tristate buffer to block miso message while reading other ICs, worked…but now I got stocked. my adc don't read the right values and jumping. I also have a conflicts with different spi clock req. rate. Some source on the internet wrote that this a clear sign for spi error…
VDD is stable at 3,31V and adc channel 0-6 is stable at 1,647V. So dial position should be around 32.75…
I have tried three different pairs of mcp6004 op amps and mcp3208.
I also connected a brand new mcp3208 to axo and a breadboard and recorded axo<->adc spi communication by logic sniffer.
maximum analog<->digital ground resistance is not higher then 0,1Ω...
1. test round
ADC CH0 = VDD = Axoloti hex object: 0x87FF0000
ADC CH0 = 1,647V = Axoloti hex object: 0x83D40000 or 0x83E40000
ADC CH0 = GND = Axoloti hex object: 0x00800000
I got the same results with adc on breadboard and axoloti only.
Does anyone have any suggestions to solve this problem?
current prototype revision schmeatic