High rate serial logging

RE: High rate serial logging

Kenneth — Thu, 16 Aug 2018 08:51:22 GMT

I assume that a problem may be that it is difficult in hardware to generate an accurate 912600baud from the internal clock (not easily to divide), likely the baud rate will be off (with a few %), though this should potentially corrupt bytes, not skip bytes. In any case it would be better if you could use 10000000baud, this should be accurate.

I tried the \examples\temperature from SDKv15 by setting it to to max baudrate (1M) in sdk_config.h, and removed the nrf_delay_ms(500) in the while loop. I also manually started the HFCLK to have an accurate clock by:

    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_HFCLKSTART = 1;
    while(NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;

This seems to print at least the following in a loop without any issue:

Maybe you can test it for comparison?

RE: High rate serial logging

ohtap — Thu, 16 Aug 2018 08:11:45 GMT

The same behavior appears when HWFC is disabled.

Channel 1 for CTS, channel 2 for TX, 3 for RTS.

RE: High rate serial logging

Kenneth — Thu, 16 Aug 2018 07:17:47 GMT

Can you try to disable HWFC and/or also record the RTC/CTS lines?

Best regards,
Kenneth

RE: High rate serial logging

ohtap — Wed, 15 Aug 2018 15:11:33 GMT

I'm attaching screenshots in various zoom levels. There are periods with gaps where the channel is "static" but should contain data transmissions.

RE: High rate serial logging

Kenneth — Wed, 15 Aug 2018 12:24:09 GMT

Is there any way you can share with me a screenshot of what it looks like when it fails on the logic analyzer? I want to see if bytes are skipped, corrupted etc.

Best regards,
Kenneth

RE: High rate serial logging

ohtap — Wed, 15 Aug 2018 11:04:22 GMT

Hi,

I've connected Pin 6 (TX) to a logic analyzer.

When not transmitting the channel is clean without any noticeable noise.

The first 240 characters are always printed correctly on the terminal.

I suspect this has something to do with bad configuration on my part...

I've integrated this as part of the ATT_MTU Throughput example , so I'm relying mostly on the configuration used in the example, with the Baudrate set now at 1M on both the sdk_config.h and on the terminal.

RE: High rate serial logging

Kenneth — Tue, 14 Aug 2018 14:15:20 GMT

Hi,

Have you looked at a logic analyzer trace when transmitting 240bytes only?

This can identify if the problem is the USB to UART bridge (you may try a FTDI chip if possible) or if the problem is the UART driver on the nRF52.

Best regards,
Kenneth