Increase MOTOR_CURRENT_PWM_RANGE to 2900 for Ultimain2 boards #27705
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Description
I noticed that using the Marlin 2.x.x firmware the steppers would run significantly hotter over the stock Ultimaker OEM Marlin firmware for the Ultimain2 boards - eventually leading to the stepper drivers overheating. I originally had to reduce the stepper current drives to absurdly low levels until I read the schematics of the Ultimain 2 boards to see why:
Referencing the pcb schematics found here and the A4988 stepper drivers datasheet found here
The RC circuit is used to convert the 5V pwm signal to an analog signal according to this image (circled in red):
At 100% duty cycle we effectively have a voltage divider circuit that feeds into VREF (R1 = 2k and R2 = 604 Ohms) 1.16V.
Using the current formula from page 9 of the datasheet (and RS = 0.05 Ohms from the datasheet):
The current limit of the stepper driver is effectively 2.9 Amps. Thus the range of 2000 mA in the current configuration found in pins_ULTIMAIN_2.h is incorrect and should be increased.
I personally was sitting on this change for years and ran this on my Ultimaker Original Plus. The steppers and drivers no longer overheat with this change applied.
Requirements
Ultimaker with Ultimain2 board installed (UMO+/UM2/UM3)
Benefits
Fix overheating of stepper motors and drivers during normal use when the current is set to the ultimaker defaults.
Configurations
Use the default configurations for Ultimaker Original Plus/Ultimaker 2 found in the examples folder of MarlinFirmware/Configurations
Related Issues
No known related issues so far.