I have installed Tinyfab smoothie board on my Cetus3 Extended Printer, my heatbed thermistor reads correct but my hotend thermistor reads 12 degrees lower. I have copied the original settings from my version 4 config (using version 6 now) but not able to get a correct reading. Anyone have an idea?
I have spent hours this week trying to get an accurate reading from the TinyFab heatbed thermistor (NTC 100k) via the opamp buffer circuit on the new beta board. The way the voltage divider has been laid out (to suit the stock CPU evidently) causes an inverted temp reading. I messed around with config for hours before I realised that on the underside of the TinyFab CPU is a 4 pin JST connector for the separate heatbed MOSFET driver that is connected to a voltage divider on the CPU PCB that puts the thermistor on the GND side of the series resistor pair: By connecting the TinyFab heatbed thermistor SEN+ and SEN- to pins 3 and 2 of the TinyFab CPU underside connector and using the config below (CPU input 0.26 and beta 3950) I was able to again get an accurate bed temp reading and use the onboard heatbed MOSFET driver and shared 24V power source without requiring the external TinyFab heatbed driver board. temperature_control.bed.enable true
Got my TMC2209s and everything is installed and working correctly. Note: The direction pin of these is inverted compared to the defaults. I set them up with 64 microsteps in stealth chop and adjusted the reference voltages o 0.15V. The motors are totally silent. So much that I forgot I had prints running. Tried setting the extruder with spread cycle but it had a horrible high pitch whine, so I went back to stealth chop. I had to increase the max PWM of the hotend a little since I was having trouble reaching >210° with the original settings. I did have some problems getting the heatbed thermistor to recognize a good temperature. I see in the schematic that the new board uses a voltage follower, so I updated the config a little and I get ~30° ambient, and ~70° when hot, which I know is more like 60 but I can live with that. Wire management is up next, but I've been having too much fun printing for that :D. I'm attaching my config file in case it's useful for someone.