INA229: No response on MISO line,i'm trying to read the device register ,mosi line is fine but their is no response from ina229 ,the attached image as the spi config

Yeah,I tired with mode 1 ,cpol=0,cpha=1 but no reponse on the miso line .I observed only small spike

What should be spidata width? And is it necessary to config ina229 before reading device register? And how vbus should connected if not using?

Hello Saiprakash,

In that case, I recommend that you double check logic threshold levels and timing requirements. For the logic thresholds, you will need to make sure that the logic low is below 0.4V compared to the INA (this is the most common mistake I see). Also, the INA will need to share GND with the MCU and measured Load. Here are the timing requirements (may need to click image to enlarge):

If you are still having problems after checking the timing requirements and logic levels, then please send me a schematic to look over. It may also be helpful to have an oscilloscope shot of the transaction, as opposed to the logic analyzer view, so that I can see levels and noise more easily. If you are not using VBUS, then it is fine to leave floating, but you can also connect to GND if you want. Some register values may read 0 if not configured, so I recommend testing communication with the MANUFACTURER_ID and DEVICE_ID registers.

Regards,

Mitch