Powering down RAM sections increases current

RE: Powering down RAM sections increases current

SUK — Thu, 16 Mar 2017 16:09:33 GMT

Changing the for loop location solved my problem. The current is now in uA. Thank you so much for helping out Stian and Wojtek.

SUK

RE: Powering down RAM sections increases current

Stian Røed Hafskjold — Thu, 16 Mar 2017 15:53:53 GMT

Please see my updated answer. You only have to use the POWERCLR register.

RE: Powering down RAM sections increases current

SUK — Thu, 16 Mar 2017 14:55:31 GMT

Yes I did. Same result. Infact, if I just power down section 4 of RAM, the current consumption has shot to 9 mA. Are these values correct:

NRF_POWER->RAM[4].POWER = 0;
NRF_POWER->RAM[4].POWERCLR = 0x00030003;

Do I need to use both statements or either one is fine?

RE: Powering down RAM sections increases current

Wojtek — Thu, 16 Mar 2017 14:51:48 GMT

It looks ok, did you rebuild (clean, build) whole project before trying?

RE: Powering down RAM sections increases current

SUK — Thu, 16 Mar 2017 14:50:50 GMT

If I don't power down any of the RAM sections, my current consumption is around 2 micro Amps. This is very confusing. Except for the softdevice, nothing is powered on in my code. Yes I am using GCC with Eclipse Mars.

RE: Powering down RAM sections increases current

Stian Røed Hafskjold — Thu, 16 Mar 2017 14:48:11 GMT

sorry, didn't see your last comment..

RE: Powering down RAM sections increases current

Stian Røed Hafskjold — Thu, 16 Mar 2017 14:47:28 GMT

How does your linker script look now? Are you using GCC? Are you sure it's not the code itself that fails? If you set i = 4/5/6.. etc, the current consumption looks fine?

RE: Powering down RAM sections increases current

SUK — Thu, 16 Mar 2017 14:44:59 GMT

Please find below the memory configuration. The memory config is using section 7 of RAM to store non initialized RAM data. Hence I tried powering down sections from 3 to 6 keeping section 7 powered up. But still the same result.

    /* Linker script to configure memory regions. */

SEARCH_DIR(.)
GROUP(-lgcc -lc -lnosys)

MEMORY
{
  FLASH (rx) : ORIGIN = 0x1c000, LENGTH = 0x58000
  RAM (rwx) :  ORIGIN = 0x20002080, LENGTH = 0x3000 
  
  /** Location of non initialized RAM. Non initialized RAM is used for exchanging bond information
   *  from application to bootloader when using buttonluss DFU OTA or exchanging bootloader version
	*	information from bootloader to application. 
   */
  NOINIT (rwx) :  ORIGIN = 0x2000FF80, LENGTH = 0x80
}

SECTIONS
{
  .fs_data :
  {
    PROVIDE(__start_fs_data = .);
    KEEP(*(.fs_data))
    PROVIDE(__stop_fs_data = .);
  } > RAM

  /* No init RAM section in bootloader. Used for app/boot information exchange. */
  .noinit(NOLOAD) :
  {

  } > NOINIT
} INSERT AFTER .data;

INCLUDE "nrf52_common.ld"

RE: Powering down RAM sections increases current

Wojtek — Thu, 16 Mar 2017 14:39:17 GMT

Pls post screen of your memory configuration.

RE: Powering down RAM sections increases current

SUK — Thu, 16 Mar 2017 14:29:59 GMT

Hi Stian, Thank you for your reply. I have modified my code to power only 3 RAM sections and power down the remaining ones. But the current consumption is still high. Any ideas on that? Thanks, SUK

RE: Powering down RAM sections increases current

SUK — Thu, 16 Mar 2017 14:28:21 GMT

Hi Wojtek, Thank you for answering. I have modified my code to power down sections 3 to 7. But still my current consumption is in mA. Any ideas on that? I have attached the modified code below.

int main(void)

{ nrf_clock_lf_cfg_t clock_lf_cfg = { .source = NRF_CLOCK_LF_SRC_RC, .rc_ctiv = 16, .rc_temp_ctiv = 2, .xtal_accuracy = NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM};

// Initialize the SoftDevice handler module.
SOFTDEVICE_HANDLER_INIT(&clock_lf_cfg, NULL);

for (uint8_t i = 3; i < 8; i++)
{
        NRF_POWER->RAM[i].POWER = 0;
        NRF_POWER->RAM[i].POWERCLR = 0x00030003;
}

sd_power_mode_set(NRF_POWER_MODE_LOWPWR);

while (true)
{
        sd_app_evt_wait();
}

return 0;

}

Thanks, SUK

RE: Powering down RAM sections increases current

Stian Røed Hafskjold — Thu, 16 Mar 2017 12:13:54 GMT

I'm not sure if I understand your calculations correctly, but anyways, RAM ORIGIN is where the application RAM starts after the Softdevice RAM, and then you have the size of the application RAM.

So lets say you want to power 2 RAM sections. That equals 16k = 0x4000.

RAM starts at 0x2000 0000
Softdevice ends at 0x2000 2080 (This depends on the SD configuration; using the numbers in your question)
Then you have 0x4000 - 0x2080 = 0x1F80 left for the application.

So the values in the linker script should then be,

RAM (rwx) : ORIGIN = 0x20002080, LENGTH = 0x1F80

EDIT

I ran your code and I got the same result. The problem is that you're turning of RAM after the SOFTDEVICE_HANDLER_INIT(). There's a protection mechanism in the SD. Move the for loop to the start of main() and you should be fine. Or you can use the SD call for turning of RAM, sd_power_ram_power_clr().

RE: Powering down RAM sections increases current

Wojtek — Thu, 16 Mar 2017 11:47:07 GMT

0x20002080 + 0x2EA8 = 0x20004F28. So, You are using RAM0-2 blocks. RAM begins at 0x20000000, not 0x20002080. It is 0x20002080 because 0x2080 is reserved for SoftDevice.