Hi,
I'm having difficulty configuring temperature input for a heated bed on a Ramps 1.4 board.
The extruder input works correctly, but the bed input tracks the extruder input with a small offset.
I know from experience that this means the analog input being sampled is electrically isolated and the ADC is measuring the residual charge from the previous channel instead.
I have verified the electrical connection from the thermistor inputs to the analog inputs A13-A15 on the Arduino, and that the voltages are correct for the temperatures being read.
I've also checked Marlin to ensure that the correct board configuration is selected ( RAMPS_14_EFB ) and that the thermistor pin assignments in this configuration are A15, A13, A14.
I've also uploaded a simple program to read each of those ports and print the values to serial. The values read are correct.
Hardware is correct, firmware appears to be configured correctly, so why is Marlin giving complete bogus temperatures for the heated bed?
Cheers
