Elecrow Arduino CNC Shield V3.51 - GRBL v0.9 Compatible

This is a high quality product and it works well. However I am not using it for its intended CNC application but simply as a physical platform for three stepper drivers plus I2C. The steppers ran fine but the I2C would not. The snag I found was that the SCL line has a pull-up to Vdd and this prevents the I2C from working. it was not a good idea to lift the resistor so I simply isolated the SCL line and connected directly to the UNO. There is no diagram that I can find that reflects the wiring of this version with its pull-up resistors for example and so it required probing with a DVM to uncover the problem. I realize I am using it outside its intended application but nevertheless there should be a correct schematic available for troubleshooting.

The pwm and probe ports are well worth the upgrade from the v3 board.

Worth buying this original over the problematic Asian clones. V3.51 has enough improvements to make it worthwhile upgrading over the previous versions. Great way to squeeze out every bit of GRBL capability in an easy-to-use package. I too would like to see schematics published, but understand the manufacturer's reluctance.