Unstable UA reading

[ciepanek]

Hi! I've made my own board based on shield 2 schematic. Everything is working fine(no errors, lambda is heating etc..) but reading from UA is very unstable. This is log from serial board:

Measuring, CJ125: 0x28ff, UA_ADC: 910, UR_ADC: 173, UB_ADC: 241, Lambda: -, AFR: 148.75, VB: 12.96
Measuring, CJ125: 0x28ff, UA_ADC: 847, UR_ADC: 173, UB_ADC: 250, Lambda: -, AFR: 148.75, VB: 13.44
Measuring, CJ125: 0x28ff, UA_ADC: 840, UR_ADC: 172, UB_ADC: 256, Lambda: -, AFR: 148.75, VB: 13.76
Measuring, CJ125: 0x28ff, UA_ADC: 877, UR_ADC: 173, UB_ADC: 250, Lambda: -, AFR: 148.75, VB: 13.44
Measuring, CJ125: 0x28ff, UA_ADC: 756, UR_ADC: 172, UB_ADC: 249, Lambda: 6.38, AFR: 93.84, VB: 13.39
Measuring, CJ125: 0x28ff, UA_ADC: 882, UR_ADC: 173, UB_ADC: 240, Lambda: -, AFR: 148.75, VB: 12.90
Measuring, CJ125: 0x28ff, UA_ADC: 777, UR_ADC: 173, UB_ADC: 252, Lambda: 8.23, AFR: 121.04, VB: 13.55
Measuring, CJ125: 0x28ff, UA_ADC: 875, UR_ADC: 173, UB_ADC: 250, Lambda: -, AFR: 148.75, VB: 13.44
Measuring, CJ125: 0x28ff, UA_ADC: 809, UR_ADC: 173, UB_ADC: 240, Lambda: -, AFR: 148.75, VB: 12.90
Measuring, CJ125: 0x28ff, UA_ADC: 878, UR_ADC: 172, UB_ADC: 250, Lambda: -, AFR: 148.75, VB: 13.44
Measuring, CJ125: 0x28ff, UA_ADC: 795, UR_ADC: 173, UB_ADC: 250, Lambda: -, AFR: 148.75, VB: 13.44

Lambda sensor is new and i've checked it with Innovate lc2. I was also replaced CJ125 with another one but UA reading wasn't changed.

I have already ordered original board from BYLUND to my another car but i want this one to get working because I want to expand it with CAN BUS, DAC etc.
Cheers

[Christian_Bylund]

Hi, are you sure you are reading from the right ADC-input?

It looks like you are reading from a floating analog input pin.