Low power mode running MyNewt on nrf52832 DK

RE: Low power mode running MyNewt on nrf52832 DK

Min-Ching Ho — Thu, 14 Feb 2019 18:27:37 GMT

Got an answer for this one from FAE. I hit Erratum 89.

https://www.nordicsemi.com/DocLib/Content/Errata/nRF52832_Rev2/latest/ERR/nRF52832/Rev2/latest/anomaly_832_89

There is another post on the forum also point out the same thing.

https://devzone.nordicsemi.com/f/nordic-q-a/42145/spim-easydma-to-increase-power-consumption/163946#163946

After I applied the workaround, the current went down.

FYI.

Min-Ching

RE: Low power mode running MyNewt on nrf52832 DK

Min-Ching Ho — Wed, 13 Feb 2019 16:32:55 GMT

I have figured the root cause after I got some help from local FAE team. But, the solution is not clear now.

The SPIM1 actually prevent the system turning off HFXO. It came down to a function call we used in our driver. In MyNewt project, it offers several APIs to write/read the data via SPI. You can find the code here: https://github.com/apache/mynewt-core/blob/master/hw/mcu/nordic/nrf52xxx/src/hal_spi.c. One way is to write byte by byte and poll the status, “hal_spi_txrx()”. The other way is to leverage TASKS, “hal_spi_txrx_noblock()”. Still waiting for further information.

Min-Ching

RE: Low power mode running MyNewt on nrf52832 DK

Min-Ching Ho — Tue, 12 Feb 2019 05:22:12 GMT

I would like to share my test code here. FYI.

enter_sleep_mode_cb(struct os_event *ev)

{

power_mode_e state = *(power_mode_e *)ev->ev_arg;

if(state == POWER_STATE_NONE)

{

// overwrite the power state

;

}

// call hal power API

hal_bsp_power_state(state);

//1. put peripheral into sleep

// excluded all driver code for test

// Turn off UART/SPI/I2C

hal_uart_stop_tx(0);

hal_uart_stop_rx(0);

// uart is turned off here by os_dev_suspend_all

os_dev_suspend_all(0xFFFFFFFF, 1);

// turn off timer

hal_timer_deinit(0);

hal_timer_deinit(1);

hal_timer_deinit(2);

hal_timer_deinit(3);

hal_timer_deinit(4);

//disable i2c

hal_i2c_disable(0);

//disable spi

hal_spi_disable(1);

// turn off GPIOE

//something new from mynewt

NRF_CLOCK->TASKS_HFCLKSTOP = 1;

//2. put CPU into wait for event mode

// Wait for an event

__WFI();

// clear the internal event register

__SEV();

__WFI();

//3. wake up process

// enable UART/SPI/I2C

//4. wake up complete

//console_printf("System awake\r\n");

}

RE: Low power mode running MyNewt on nrf52832 DK

Min-Ching Ho — Mon, 11 Feb 2019 18:57:35 GMT

Hi Siguard,

Sorry for late reply. I was out of office. I already tried this. It didn't work. I still see the current is >270uA.

Any other suggestions?

Min-Ching

RE: Low power mode running MyNewt on nrf52832 DK

Sigurd — Tue, 29 Jan 2019 16:40:26 GMT

Could you try to stop the UART transmitter/receiver, before disabling it ?

NRF_UARTE0->TASKS_STOPRX = 1;
NRF_UARTE0->TASKS_STOPTX = 1;

RE: Low power mode running MyNewt on nrf52832 DK

Min-Ching Ho — Mon, 28 Jan 2019 11:38:05 GMT

Hi Siguard,

Thanks for the info. It looks like my HFCLK is still up and running. One thing I didn't mentioned in my original post is I did disable UART before WFE. Is there a way to check which peripheral is still using HFCLK?

Thank you,

Min-Ching

RE: Low power mode running MyNewt on nrf52832 DK

Sigurd — Thu, 24 Jan 2019 13:12:47 GMT

Hi,

[quote user=""]except UART for console and debug messages.[/quote]

UART peripheral requires HFCLK and if you run HFCLK with the 64MHz crystal current consumption will be ~250uA.

RE: Low power mode running MyNewt on nrf52832 DK

natersoz — Thu, 24 Jan 2019 03:55:40 GMT

My experience:

ARM typically calls waiting in WFE "sleep" and Nordic stays consistent with this terminology.

Waiting in sleep mode is not sufficient to get down to < 10 uA power draw.

You need to:

1.Disable all of the peripherals possible, except for the peripheral that is going to wake you up (GPIO pin? timer/RTC?)

2. halt the CPU to 'standby' - the CPU clock actually stops.

Then you can start shaving down the uA draw currents (what did you leave on? Are all the GPIO pins set to their minimal power? etc.)