Problem with BLE Low Power Mode

RE: Problem with BLE Low Power Mode

Susheel Nuguru — Tue, 10 Jul 2018 09:43:49 GMT

UART with or without FIFO should work the same way power efficiency wise. UART FIFO just has very very tiny overhead of managing the buffer, but you should not see that big difference.

[quote user="john_h"]Turns out that calling sd_app_evt_wait() twice does the trick[/quote]

This smells like a bug in the FIFO code somewhere. Thanks for the workaround, I did not find any other customer having this problem. I will anyways asks the team to do some power measurements on both to compare. Can we close this case John?

RE: Problem with BLE Low Power Mode

john_h — Thu, 05 Jul 2018 18:57:07 GMT

Hi Aryan,

Looks like I have resolved this for now. Turns out that calling sd_app_evt_wait() twice does the trick and puts it into low power mode consistently.
Do you have any idea if the UART FIFO vs normal UART would have any affect on the low power mode?

RE: Problem with BLE Low Power Mode

Susheel Nuguru — Wed, 04 Jul 2018 10:17:26 GMT

It looks like in your code snippet, you are trying to uninitialize the UART before you are calling app_uart_init.

Please check in a debugger to see if when using app_fifo and when calling nrf_drv_uart_rx_disable/app_uart_close fails with a return code and is stuck in the app_error handler?

RE: Problem with BLE Low Power Mode

john_h — Tue, 03 Jul 2018 21:35:50 GMT

As a note... I was able to get it into the lowest power mode when I switched to the non-FIFO uart. Is there any reason for this?

RE: Problem with BLE Low Power Mode

Susheel Nuguru — Tue, 03 Jul 2018 19:42:23 GMT

If this is all I need, then i will test this tomorrow morning as its pretty late here in Norway

RE: Problem with BLE Low Power Mode

john_h — Tue, 03 Jul 2018 19:03:50 GMT

I think should be enough. I also have events for ble connections but shouldn't be an issue. I am using version 12.3 with s130

All my uart init/uninit is in uart library app_uart_fifo.c which is very similar to app_uart.c. I moved some of the code out of there and into this snippet just to make it more clear.

RE: Problem with BLE Low Power Mode

Susheel Nuguru — Tue, 03 Jul 2018 19:01:08 GMT

seems like the uart uninit function is leaving something enabled. I would have to reproduce this tomorrow, which SDK version did you use? Is the code snippet you attached, enough for me to be able to reproduce this issue?