How to reach nRF52840 UARTE current supply specification ?

RE: How to reach nRF52840 UARTE current supply specification ?

Anton K. — Fri, 11 Sep 2020 12:11:05 GMT

Hi, 3 years latter I meet this problem, which was not fixed by NORDIC. Actually for me sequence works fine:

*(volatile uint32_t *)0x40002FFC = 0;
*(volatile uint32_t *)0x40002FFC = 1;



But sequence via second way doesn't work:
nrf_drv_uart_rx_abort(&uart_addr);
nrf_drv_uart_tx_abort(&uart_addr);
nrf_drv_uart_uninit(&uart_addr);


Also nRF52840 Product Specification have no information about POWER register with base address of UART0/1

Can you explain about right sequence without hidden POWER register usage?
Thank you for this post.

RE: How to reach nRF52840 UARTE current supply specification ?

Luke Galea — Thu, 19 Dec 2019 11:47:06 GMT

Hi Stian, I am also experiencing this issue with the nRF UARTE Drivers in SDK 16 with the nRF52840.

My code is as follows. The uarte_uninit manages to stop the TX because if nrfx_uarte_rx is not used, a low current consumption is achieved once again. Power cycling the UARTE through the registers seems to fix the issue when nrfx_uarte_rx is used. The tx/rx abort do not seem to have any affect ...

Moreover could you provide a link to the documentation where FFC from UARTE0 offset 0x40002 is mentioned? Because I could not find this register which power cycles the UARTE0.

// Stop any reception on UARTE0
nrfx_uarte_tx_abort(&uarte0_inst);
nrfx_uarte_rx_abort(&uarte0_inst);

// Stop any reception on UARTE1
nrfx_uarte_tx_abort(&uarte1_inst);
nrfx_uarte_rx_abort(&uarte1_inst);

// Switch Off both UARTEs to reduce current consumption
nrfx_uarte_uninit(&uarte0_inst);
nrfx_uarte_uninit(&uarte1_inst);

// Power cycle the UARTE0 - Fix or Workaround since UARTE0 is not getting turned Off if RX is enabled
*(volatile uint32_t *)0x40002FFC = 0;
*(volatile uint32_t *)0x40002FFC;
*(volatile uint32_t *)0x40002FFC = 1;

RE: How to reach nRF52840 UARTE current supply specification ?

Rob at Digi — Tue, 22 Oct 2019 16:27:53 GMT

What is the intent of the second line of code? Are you just trying to read the register? The statement doesn't do anything, and even though it is marked volatile, many compilers will optimize it out. (Mine did.) i just want to make sure I am handling the errata properly.

RE: How to reach nRF52840 UARTE current supply specification ?

Xenoamor — Tue, 15 Oct 2019 21:18:38 GMT

I'd also be interested in seeing this be officially in the Errata. I'm seeing it in rev 2 and a few engineering samples. As of now even using NRFX v1.7.2 which calls STOPRX and STOPTX does not resolve this issue

RE: How to reach nRF52840 UARTE current supply specification ?

ThierryC — Tue, 04 Jun 2019 11:20:47 GMT

Where do we find these erratum ?

RE: How to reach nRF52840 UARTE current supply specification ?

Glen M — Thu, 30 May 2019 16:51:52 GMT

I'd just like to point out something that threw me off for a little while - If you're using UARTE1, the address you write to is 0x40028FFC.

The post above correctly points out that the UARTE1 BASE is 0x40028000, but it wasn't clear to me at first that this code is writing to the base plus an offset of 0xFFC.

RE: How to reach nRF52840 UARTE current supply specification ?

Yogeshwaran — Fri, 03 May 2019 12:57:39 GMT

I disabled APP_UART_ENABLED in sdk_config.h and commented out function relevant to uart in ble_app_uart example now it is not hanging in external power.

RE: How to reach nRF52840 UARTE current supply specification ?

Yogeshwaran — Thu, 02 May 2019 12:26:19 GMT

Thank you Stian my slrteep current is 8uA reduced from 0.92mA but my uart is still not disabled because of this if i run it in coin cell without usb it is getting hang in uart_init() function. i tired disabling both UARTE and UART0 also but no changes still it is getting hang in the coin cell power run.

if i permanently switch off uart peripheral then my current will reduce more and it won't hang in the coin cell run mode.

RE: How to reach nRF52840 UARTE current supply specification ?

Yogeshwaran — Thu, 02 May 2019 12:13:55 GMT

i am facing issue with uart_init() in ble_app_uart peripheral example. if i disable the uart in sdk_config(UART0_ENABLE 0) and i commented the uart_init() in the main function after this the sleep current is 2.5 ma and if i uncomment uart_init() my sleep current is 0.92mA system_on mode. The device hangs if run in coin cell because of uart.

so why this is happening and how to permanently disable the uart function in ble_app_uart without affecting other operations?

RE: How to reach nRF52840 UARTE current supply specification ?

vishal — Thu, 28 Mar 2019 11:15:58 GMT

I am also using facing this issue after update this above workaround the power consumption is decreased. But I got another problem When UART disabled my device switch sense not detect. Why this happening?

Thanks..

RE: How to reach nRF52840 UARTE current supply specification ?

Tim — Fri, 21 Dec 2018 11:08:08 GMT

Thank you for your answer. Could you please update the errata to mention the UARTE as well ? Because we went through the errata when we encountered this issue and since the UARTE wasn't mentioned, we didn't consider this errata.

RE: How to reach nRF52840 UARTE current supply specification ?

Francois5Co — Wed, 01 Nov 2017 15:21:47 GMT

Thanks for your reply. It works. But if I want to put the uart in idle mode with hw flow control (not close it), to wake up when it start receiving uart message, how can I minimize current consumption ?

RE: How to reach nRF52840 UARTE current supply specification ?

Stian Røed Hafskjold — Wed, 01 Nov 2017 14:45:03 GMT

First of all, 0.8 mA (on nRF52840, no DCDC. 0.35 mA with DCDC enabled @3V) is the expected run current for the UARTE in RX or TX mode since HF clock is needed and the DMA bus is active.

When you call app_uart_close() basically what happens is that the peripheral is disabled by writing 0 to the NRF_UARTE0->ENABLE register. Unfortunately, this seems to not stop the HF clk and close the DMA bus, which could be a bug. However, if you power cycle the peripheral after calling app_uart_close() the current consumption goes down. You can do that with this code:

*(volatile uint32_t *)0x40002FFC = 0;
*(volatile uint32_t *)0x40002FFC;
*(volatile uint32_t *)0x40002FFC = 1;

If you are using UARTE1 the base address is 0x40028000. infocenter.nordicsemi.com/.../uarte.html

EDIT:

Just adding that the UARTE TX has to be stopped explicitly when it's finished. If you just close the UART without stopping the transactions the UART will continue to keep the clocks running, as described above.

This can be done through the nrfx_uarte_tx/rx_abort() functions, or the TASKS_STOPRX/TX registers directly.

If you do this before disabling the UART the above workaround is not needed.

RE: How to reach nRF52840 UARTE current supply specification ?

Stian Røed Hafskjold — Wed, 01 Nov 2017 13:37:42 GMT

Sorry, Martin is out travelig now. I will take a look at this.

RE: How to reach nRF52840 UARTE current supply specification ?

Francois5Co — Mon, 30 Oct 2017 06:07:09 GMT

Any News ?

RE: How to reach nRF52840 UARTE current supply specification ?

Francois5Co — Fri, 20 Oct 2017 10:52:21 GMT

Thanks a lot for your help

RE: How to reach nRF52840 UARTE current supply specification ?

MartinBL — Fri, 20 Oct 2017 10:22:21 GMT

I'm have done some tests and I see the same thing. I'm looking for a workaround, but it might take a few days.

RE: How to reach nRF52840 UARTE current supply specification ?

Francois5Co — Wed, 18 Oct 2017 12:21:34 GMT

Yes I have tried flow control and it doesn't really change the current supply. The "NRF_UARTE0->TASKS_STOPRX = 1" doesn't change the current supply.

RE: How to reach nRF52840 UARTE current supply specification ?

MartinBL — Wed, 18 Oct 2017 12:09:33 GMT

hi,

Have you tried using flow control?

Can you try to put NRF_UARTE0->TASKS_STOPRX = 1; after uart_init()?