change DCCH to 3.3V uart not work

Hi,

Can you explain what you mean by "uart will can not work"? What device are you communication with through the UART peripheral?

change pin to high voltage as follow two lines not working;

nrf_gpio_cfg_output(0x24); 
nrf_gpio_pin_set(0x24);

What is not working? Do the pin not get set as you expect? Did you measure the GPIO/VDD voltage using a voltmeter?

Have you made sure that the UICR->REGOUT0 register is erased before writing the UICR_REGOUT0_VOUT_3V3 value? The UICR registers works like flash, which means that bits can only be written from 1 to 0, not from 0 to 1. Changing a bit from 0 to 1 requires you to erase the full UICR. If REGOUT0 already contains another value, you may end up in a situation where you write the register to an unsupported value.

Note that the nRF21540 DK will work in normal voltage mode when powered through the J2 USB connector. In this mode, the nRF52840 chip will be powered by a 3V regulator, and the REGOUT0 register config will not have any effect. See nRF21540 and nRF52840 power source for more details.

Best regards,
Jørgen

Hi,

thanks for reply,

full project code:

void gpio_output_voltage_3v3()
{
    NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
    while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

    NRF_UICR->REGOUT0 = (NRF_UICR->REGOUT0 & ~((uint32_t)UICR_REGOUT0_VOUT_Msk)) |
                        (UICR_REGOUT0_VOUT_3V3 << UICR_REGOUT0_VOUT_Pos);

    NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
    while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

    // System reset is needed to update UICR registers.
    NVIC_SystemReset();
}
int main(void)
{
	gpio_output_voltage_3v3(); //1V8 change to 3V3
	
	nrf_gpio_cfg_output(0x24);
	nrf_gpio_pin_set(0x24); //pull high
	
	uint32_t err_code=0;
	const app_uart_comm_params_t comm_params =
	{
			RX_PIN_NUMBER,
			TX_PIN_NUMBER,
			NULL,NULL,
			APP_UART_FLOW_CONTROL_DISABLED,
			false,
			NRF_UART_BAUDRATE_115200
	};
	APP_UART_FIFO_INIT(&comm_params,
											 UART_RX_BUF_SIZE, UART_TX_BUF_SIZE,
											 uart_error_handle, APP_IRQ_PRIORITY_LOWEST,
											 err_code);
	APP_ERROR_CHECK(err_code);

	printf("Btest start......\r\n");

	while(1)
	{
		app_uart_put('s');
		nrf_delay_ms(1500);
	}
	return 0;
}

uart device is usb serial port for windows, it work well when default DCCH 1.8V vlotage.

windows can recive logs:

nrf_gpio_pin_set(0x24);  the pin 0x24 voltage is 3.25V.

  -------------------------------------------------------------------------------------------------

Did you measure the GPIO/VDD voltage using a voltmeter? yes

when change DCCH to 3.3V as above codes in main first,

(1). the uart will can not recive logs ,

(2). nrf_gpio_pin_set(0x24);  the pin 0x24 voltage is 0V.

Have you made sure that the UICR->REGOUT0 register is erased before writing the UICR_REGOUT0_VOUT_3V3 value? i don't konw how to make sure it,please see full code above.

Best regards

Hi,

thanks for reply,

full project code:

void gpio_output_voltage_3v3()
{
    NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
    while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

    NRF_UICR->REGOUT0 = (NRF_UICR->REGOUT0 & ~((uint32_t)UICR_REGOUT0_VOUT_Msk)) |
                        (UICR_REGOUT0_VOUT_3V3 << UICR_REGOUT0_VOUT_Pos);

    NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
    while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

    // System reset is needed to update UICR registers.
    NVIC_SystemReset();
}
int main(void)
{
	gpio_output_voltage_3v3(); //1V8 change to 3V3
	
	nrf_gpio_cfg_output(0x24);
	nrf_gpio_pin_set(0x24); //pull high
	
	uint32_t err_code=0;
	const app_uart_comm_params_t comm_params =
	{
			RX_PIN_NUMBER,
			TX_PIN_NUMBER,
			NULL,NULL,
			APP_UART_FLOW_CONTROL_DISABLED,
			false,
			NRF_UART_BAUDRATE_115200
	};
	APP_UART_FIFO_INIT(&comm_params,
											 UART_RX_BUF_SIZE, UART_TX_BUF_SIZE,
											 uart_error_handle, APP_IRQ_PRIORITY_LOWEST,
											 err_code);
	APP_ERROR_CHECK(err_code);

	printf("Btest start......\r\n");

	while(1)
	{
		app_uart_put('s');
		nrf_delay_ms(1500);
	}
	return 0;
}

uart device is usb serial port for windows, it work well when default DCCH 1.8V vlotage.

windows can recive logs:

nrf_gpio_pin_set(0x24);  the pin 0x24 voltage is 3.25V.

  -------------------------------------------------------------------------------------------------

Did you measure the GPIO/VDD voltage using a voltmeter? yes

when change DCCH to 3.3V as above codes in main first,

(1). the uart will can not recive logs ,

(2). nrf_gpio_pin_set(0x24);  the pin 0x24 voltage is 0V.

Have you made sure that the UICR->REGOUT0 register is erased before writing the UICR_REGOUT0_VOUT_3V3 value? i don't konw how to make sure it,please see full code above.

Best regards