Hi,
We have designed a board with 3 DRV8825 Drivers. The main controller is STM32 uC with configuration interface(Microstepping, Reset, Enable, Direction, Decay etc) through 74HC595 & 3 separate PWMs for each. Power supply for Motor & Controller is Dual Output SMPS with ratings of 24VDC/4A & 12VDC/1.5A.
Note that 595 shift registers & DRV8825 are on same PCB while STM32 is on separate PCB with single FRC cable used for inter-connect.
I am able to configure DRV8825 correctly through SPI of STM32 The issue we're facing is that sometimes while starting the motors or sometimes while motors are running it resets all shift registers making all of its output 0, leading to reset of all DRV8825. Note that there is no activity on any of shift-registers lines when this happens.
1) I assumed that it may be issue with shift registers of noise interfering & tried many things, but issue isn't solved.I am unable to catch any glitches on SPI lines with my scope.
2) Also using 2 separate power supplies sometimes masks the issue, but in the long run shift-registers get reset.
3) Interestingly, we've another configuration using exact same motors, same power supply. Only Shift registers are on STM32 PCB while we've 3 separate DRV8825 boards inter-connected through 3 FRC cables. It's been running without any issues for last 12 months 24x7.
So is it possible to have multiple DRV8825s on same PCB, sharing common Power Supply tracks(+VM & GND)? Or issue is still with shift-registers?
I am attaching images of TOP & BOTTOM layers of my DRV8825 PCB.
Any help will be greatly appreciated.
Thanks in advance.