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I recently used this chip in my first-ever PCB design. I'm having trouble getting it to transition from INIT2 state to STANDBY. In doing more digging, I suspect I may have found the issue but wanted to get confirmation if possible.
Because this is the only SPI device on the board, I permanently asserted the nSCS (Chip Select - Pin 2) low to save IOs on the MCU. But I see in the datasheet that "nSCS should be pulled high between words" and now I suspect that my not having that transition could be my problem.
Can anyone confirm that a state transition on nSCS is required (or not) for SPI communication to work?
Appreciate any help!
Hey Mikah,
Yeah, unfortunately for SPI communication the nSCS pin does have to change for each frame that is sent, it helps signify to the device the beginning and end of the SPI transaction. Sounds like you found Figure 7-1. SPI Peripheral-Mode Timing Definition which gives a good visual overview for how the SPI frame should look like. Also see 8.5.1 SPI Interface.
Regards,
Jacob
Thank you Jacob! Not the news I wanted, but it's what I expected. I appreciate your help!
Hey Jacob - as a follow-up to this, I have jumpered in a Chip Select pin, but I still cannot get any response from the DRV8145 on the SDO line. Upon doing more reading, I now realize I've also left the nSLEEP pin disconnected. Safe to assume that, absent any "wakeup" signal from nSLEEP going high, I shouldn't expect any response on SDO even when I push bits in SDI?
Going to try to hand solder a jumper to Pin3 this weekend... Seems unlikely to be successful :D
Hi Mikah,
That is correct, the nSLEEP pin will need to be held high to be awake.
Best,
David