Driving three 36v4 drivers from arduino running grbl

I will be using three sets of 36v4 driver+nano to drive three stepper motors(x,y,z axis). I will also be using another arduino running grbl. How do I connect the arduino running grbl to the three nanos connected to driver’s ?

Do I just need to connect the Step & Dir pins directly to the arduino running grbl ( instead of connecting to the nano’s) ?

I did some more research and one option is to just use the one arduino which is running GRBL, but the stock code will have to be modified to write the initial setup via SPI and then execute the rest of the sketch.

If I do not want to take that approach, Can I use one arduino & and the SPI bus to configure the 3 drivers via SPI and use the arduino running GRBL to drive the STEP & DIR ?


The Tic’s serial protocol allows you to control multiple Tics using a single TTL serial port, so you can control all three Tic 36v4 controllers just from your one Arduino running the GRBL program. You can find more information under the “Setting up serial control” section of the Tic Stepper Motor Controller User’s Guide.

The Tic does not have an SPI interface; it has an I2C interface, which is different from the SPI communication protocol. The Tic’s I2C interface can still be used to configure the driver’s settings in STEP/DIR mode. You can find this information under the “Setting up STEP/DIR control” section of the Tic’s user’s guide.

- Amanda

I think I’m looking to do much the same as @Webm .

I have a small CNC mill (old Shapeoko) that is run by an Arduino with GRBL 1.1 and four DRV8825 step sticks. I’m looking to beef up the machine and bought some 36v4 drivers (part # 3730).
These are not the TIC 36v4, but the base driver that relies on SPI to configure and run.

It is my understanding that GRBL will run typical Pololu step sticks using their STEP and DIR pins. The 36v4 also has these inputs, but the product page says that the 36v4 must be enabled and configured via the SPI interface before they can be used.

I think @Webm 's solution sounds good. Use a second Arduino to enable and configure all the 36v4 drivers on initial power up. Use the Arduino running unmodified GRBL to run all the 36v4 drivers via their STEP & DIR inputs.
Has this worked for you @Webm ?