CYW20719 SPI Hardware Issue

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AbFa_4663241
Level 3
Level 3
10 replies posted First solution authored 5 questions asked

I'm using CYW920719Q40EVB-01 which is connected to an evaluation board (as a SPI slave) having an MCU via SPI interface. In my code, CYW920719Q40EVB-01 is a SPI Master which is sending/receiving array of 1024 bytes to/from my Slave board. The Slave board is powered by the 3.3V supply from CYW920719Q40EVB-01, so both boards use the same voltage.

My experiments:

1- Before connecting to CYW920719Q40EVB-01 board, my SPI slave board has been tested with a similar board with good SPI communication.

2- After CYW920719Q40EVB-01 is connected to the Slave board, I noticed that the data is transmitted from the Master (CYW920719Q40EVB-01) board to slave board but the Master receives all zero data.

3- Using an oscilloscope, I noticed that the High-level on the MISO wire is about 620 mV. Please see the attached snapshot showing the CS and MISO traces.

4- When the MISO wire between the Master and Slave is disconnected, the MISO output from the Slave shows normal High level (3.3V), again connecting the MISO from the Slave to the CYW920719Q40EVB-01 brings the High-level voltage of MISO to 620 mV.

5- The MOSI wire out of CYW920719Q40EVB-01 shows normal voltage level and correct data is received by the Slave board.

6- Different situations like using Pull-Up and Pull-Down or changing SPI1 and SPI2 in SPI initialization did not fix this issue.

My questions:

Why does the MISO input on CYW20719 drops to a lower voltage while the MOSI output shows normal operation?

Is this because I'm using a defective evaluation board (CYW920719Q40EVB-01) or I'm missing something in my coding. I'm using the SPI Master example code provided for CYW920719Q40EVB-01.

Thanks!

Abi

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