nRF5340 SPIS Max Speed

[Wangshuhai]

Hi Nordic .

  We are developing an application with nRF5340. In this application, we need to use the SPI Slave feature. According to the documentation, there isn't a clear indication of the maximum clock supported under SPI Slave mode, but it states that the minimum SCK time is 125ns, which would correlate to 8M.Based on our tests, when two nRF5340 communicate via 8M SPI, it works very well. However, when we test 16M SPI communication, errors in data content occur.

  Could you tell me what is the supported SPI frequency under the SPI Slave mode?
  Looking forward to your answer.

Isaac

[Susheel Nuguru]

Hi Xuntong,

The actual minimal SCK input depends on the Master clock setup and hold time. If you have a master that is driving the clock which is faster shorter setup time and longer hold time, then you might be able to drive speeds faster than 8MHz but 16Mhz seems too high for which we might have not tested this peripheral at those speeds.

[Wangshuhai]

Hello

Thank you for your reply.

According to our setup, we use two 5340DK boards. One is configured with SPIM and set the main frequency to 128M, with SPI at a speed of 16M. The other one is configured as SPIS. It works fine with short data transfers. But when transmitting larger data, for instance, 500 or 1000, problems occur as erroneous data issues emerge from the slave device.

I've also tried to communicate with the 53 through other MCUs and found that as soon as it exceeds 8M, the data transmission and reception become abnormal.

[Susheel Nuguru]

Yes, I think this depends on the rise and hold times of the SPI clock and data lines. If the peer is influencing the rise and hold times of these pins then it is possible that the sampling of data in SPI in nRF might be effected. 

[Aditya_p]

Hi Susheel Nuguru ,

 I am trying to run the SPI examples using TFT display provided by zephyr. In that I am not able to achieve Max-Frequency. Even though I set the spi-max-freqeuency = <25000000> or spi-max-freqeuency = <30000000> I am only able to receive 16MHz of clock. Can you please help me this.

Thanks

[Susheel Nuguru]

Aditya, the actual maximum data rate depends on the master's CLK to MISO and MOSI setup and hold timing.

Also can you please create a different ticket and please give as much description about the hardware, software versions and the environment you are testing including the peer SPIM configuration.