I've been working with the DRV10975Z in attempts to drive a Maxon 351056. I have followed the quick start guide using i2c to manually write and read registers and speed with a Raspberry Pi Pico. It seems as though I can read & write eeprom and other registers correctly but no matter what I do, I cannot get the motor driver to produce voltage. I am not sure what is causing this issue but I have noticed that the Speed Command Buffer is always set to 0.
From the QSG, my motor parameters are:
- OPERATION VOLTAGE - 12V
- NUMBER OF POLES - 2
- MAXIMUM SPEED (RPM) - 9380
- MAXIMUM CURRENT - 0.294A
- R (PHASE-CT) - 10 Ohms (Measured)
- Kt (PHASEPHASE) - 71 mV/Hz
- LR CONSTANT - Unknown for now
- INERTIA - 5.1gcm^3
And I have set the following EEPROM addresses
- Phase Resistance (0x20)
- Kt (0x21)
- Disable IPD (0x2A)
- Disable ISD & Reverse Drive (0x23)
- Set Align Time to 5.3s & O2C Loop at ~80Hz (0x26)
- Set Accel Constants (0x25)
- Set Open Loop Current & Disable Break (0x24)
- Disable Closed Loop (0x2B, 0x0D)
To Run the test I write the following commands:
- Addr:0x03 --- 0x80 (Disable Sleep)
- Addr:0x02 --- 0x81 (Enable i2c speed and MSB of Speed)
- Addr:0x01 --- 0x2c ([8:0] Speed)
Effectively, I can see that the speed command changes on 0x1B but the speed command buffer on 0x1C is always 0.
If I'm correct, the speed command buffer is the actual command?
I am using a custom PCB seen in the image below. Unfortunately it was designed for the DRV10975 and not DRV10975Z; however, it is my understanding that the Zener diode is not required unless you are utilizing sleep mode, which I will not. So it is possible that my issue is related to having the inductor instead of the resistor (currently on order).
- I have tested two motor driver ICs on two separate PCBs (Same results)
- Attempted driving with analog command (Same results)
- Tested continuity between output pins on IC and motor terminal
- Verified impedance between all terminals and ground with motor disconnected
- Run commands with two separate motors and with no motor connected.
Any help would be greatly appreciated!