Unable to change VDD to 1.8V

[Mgiger]

Dear all

I am currently working with a nRF52840 Dongle, the ble_app_blinky_s140 example. 

To power some external circuits i have to set VDD to 1.8V.

Until now i tried the following approaches.

https://devzone.nordicsemi.com/f/nordic-q-a/20528/why-data-can-not-be-wrote-into-the-registers-of-nrf52840/80038#80038

by adding this two lines to the uicr_config.h

const uint32_t UICR_ADDR_EXTSUPPLY __attribute__((at(0x10001300))) __attribute__((used)) = 0xFFFFFFFF;//Enabled
const uint32_t UICR_ADDR_REGOUT0 __attribute__((at(0x10001304))) __attribute__((used)) = 0xFFFFFFF5;//3.3V

The second approach was to change the GPIO_OUTPUT_VOLTAGE_SETUP Function to 1.8V

None of these changed the Output Voltage.

Any idea why this doesn't work?

Regards

Marcel

[michel_93]

Hi,

I have found a solution for this problem by adding the following functions to the main of the blinky example.

/**
 * @brief Function to erase UICR Registers.
 */


void nvmcErase(void)       
  if (NRF_UICR->REGOUT0 != UICR_REGOUT0_VOUT_1V8) 
  {
      NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Een << NVMC_CONFIG_WEN_Pos;        //erase enable
      while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
      NRF_NVMC->ERASEUICR = NVMC_ERASEUICR_ERASEUICR_Erase << NVMC_ERASEUICR_ERASEUICR_Pos;   //erase UICR
      while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
      NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;  //read only enable
      while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
  }
}


/**
 * @brief Function for configuration of REGOUT0 register.
 */
void vddInit(void)
{
  if (NRF_UICR->REGOUT0 != UICR_REGOUT0_VOUT_1V8) 
  {
	NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos;    //write enable
	while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
	NRF_UICR->REGOUT0 = UICR_REGOUT0_VOUT_1V8;                        //configurate REGOUT0
	NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;
	while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
        NVIC_SystemReset();                                               // Reset device
  } 
}

The first function is to clear the UICR Registers. The second one then writes the UICR with the new values.

Keep in mind to delete or uncomment the bsp_board_leds_init function in the boards.c file if you use a dongle.

Also the LEDs will not work properly if you use the dongle with 1.8V.

Regards,

Michel

[Mgiger]

Hi Michel

It worked exactly as described. I have programmed the dongle over the P1 connector on the back with a nrf5280-DK. The VDD_OUT Pin is now on 1.8V as expected.

Thank you

[Jørgen Holmefjord]

WARNING: If you follow the suggestion from michel_93, you will erase the BOOTLOADER address from UICR and you will not be able to flash the Dongle from nRF Connect through the USB port, you will require a debugger connected to the SWD interface.

If you want to erase the UICR in code to update a value, you should read every register in UICR and write it back after erase to make sure no data is lost. At the very least, you need to write back the BOOTLAODER address located in register NRFFW[0].

[Mgiger]

Hi Jorgen

Thank you for the follow up. I have also recognized this. But as i now have the connector on the dongle this doesn't matter for me.

Regards

Marcel

[Jørgen Holmefjord]

That's great! I just wanted to add the warning in case anyone else came over this thread and tried this procedure, without access to a debugger.