UART1 and UART0 on nRF52833

RE: UART1 and UART0 on nRF52833

Edvin — Fri, 03 Jan 2025 13:54:08 GMT

Hello,

Sorry for the late reply. I have been out of office. I am sorry for the inconvenience.

Can you please try to capture a logic trace of the UART pins using a logic analyzer? If you have a saleae, you can save the trace and upload it here. Please specify what channels that are capturing the different pins.

Best regards,

Edvin

RE: UART1 and UART0 on nRF52833

Taylor — Wed, 25 Dec 2024 08:26:33 GMT

uart1_init(AFD_UART_RX_PIN, AFD_UART_TX_PIN, 0x0EBEE000UL);//0x0EBED000UL NRF_UART_BAUDRATE_921600 NRF_UART_BAUDRATE_1000000

bool uart1_init(uint8_t rx_pin, uint8_t tx_pin, uint32_t baud_rate)
{
    uint32_t	errCode;
	if (NRF_UARTE1->ENABLE == (UARTE_ENABLE_ENABLE_Enabled << UARTE_ENABLE_ENABLE_Pos))
	{
    	;
	}else
	{
		app_uart1_comm_params_t const comm_paramsa1 =
		{
			.rx_pin_no    = rx_pin,
			.tx_pin_no    = tx_pin,
			.rts_pin_no   = NULL,
			.cts_pin_no   = NULL,
			.flow_control = APP_UART1_FLOW_CONTROL_DISABLED,
			.use_parity   = false,
			.baud_rate    = baud_rate,
		};
		APP_UART1_FIFO_INIT(&comm_paramsa1,
							UART_RX_BUF_SIZE,
							UART_TX_BUF_SIZE,
							uart1_event_handle,
							APP_IRQ_PRIORITY_LOWEST,
							errCode);					
		APP_ERROR_CHECK(errCode);
		NRF_LOG_INFO("Uart1 open.");
	}

	return true;
}

Thank you for your reply. I tried changing these configurations, but the data loss issue is still quite severe.

RE: UART1 and UART0 on nRF52833

Taylor — Wed, 25 Dec 2024 08:24:07 GMT

[quote userid="26071" url="~/f/nordic-q-a/117206/uart1-and-uart0-on-nrf52833/514547"]If it is not an option to change the baudrate, make sure that you enable the HFXTAL. You can test in a simple application by using:[/quote]

I'm sorry for the late reply. I added this code before initializing the UART, but it caused a reset. I believe it triggered an error handling routine.I also adjusted the baud rate of both the transmitter and the nRF52833 to 1M, but data loss still occurs.

RE: UART1 and UART0 on nRF52833

hmolesworth — Wed, 11 Dec 2024 20:36:03 GMT

Following on from edvin's comments, maybe try this value (0x0EBEE000) to see if it helps; this is from nRF52832 and nRF52840, but should be the same on nRF52833:

//  --------Calculated-------------------  ---------------Documentation---------------
//  Required Register      Actual   Error  Register    Required   Actual  Error   Ok?
//  ======== =========== ======== =======  =========== ======== ======== =======  ====
//     1200, 0x0004F000,    1205, +0.416%  0x0004F000,    1200,    1205, +0.416%,   -,
//     2400, 0x0009D000,    2395, -0.208%  0x0009D000,    2400,    2396, -0.166%,   -,
//     4800, 0x0013B000,    4806, +0.125%  0x0013B000,    4800,    4808, +0.166%,   -,
//     9600, 0x00275000,    9597, -0.031%  0x00275000,    9600,    9598, -0.020%,   -,
//    14400, 0x003B0000,   14404, +0.027%  0x003AF000,   14400,   14401, +0.006%,  No,
//    19200, 0x004EA000,   19195, -0.026%  0x004EA000,   19200,   19208, +0.041%,   -,
//    28800, 0x0075F000,   28793, -0.024%  0x0075C000,   28800,   28777, -0.079%,  No,
//    38400, 0x009D5000,   38406, +0.015%  0x009D0000,   38400,   38369, -0.080%,  No,
//    57600, 0x00EBF000,   57601, +0.001%  0x00EB0000,   57600,   57554, -0.079%,  No,
//    76800, 0x013A9000,   76797, -0.003%  0x013A9000,   76800,   76923, +0.160%,   -,
//   115200, 0x01D7E000,  115203, +0.002%  0x01D60000,  115200,  115108, -0.079%,  No,
//   230400, 0x03AFC000,  230407, +0.003%  0x03B00000,  230400,  231884, +0.644%,  No,
//   250000, 0x04000000,  250000,       -  0x04000000,  250000,  250000, +0.000%,   -,
//   460800, 0x075F7000,  460800, +0.000%  0x07400000,  460800,  457143, -0.793%,  No,
//   921600, 0x0EBEE000,  921600, +0.000%  0x0F000000,  921600,  941176, +2.124%,  No,

The documentation was updated for nRF52832 (almost correctly), but it seems not for the nRF52840 and nRF52833.

RE: UART1 and UART0 on nRF52833

Edvin — Wed, 11 Dec 2024 14:20:35 GMT

Hello,

Is it a possibility to use a different baudrate? The reason I ask is that some baudrates are more off than others. Looking at the specification for the nRF52833's UART registers:

(Source)

So this is one of the baudrates with the largest difference from the target baudrate. if you can use e.g. 1M baudrate, it will be much closer to the target baudrate.

If it is not an option to change the baudrate, make sure that you enable the HFXTAL. You can test in a simple application by using:

NRF_CLOCK->TASKS_HFCLKSTART=1;
while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
{
    // Wait...
}

before starting the UART. But if your application is using some drivers that are requesting the clock in a proper way (such as BLE), then it will also release the clock properly, turning off the HFCLK. But using this snippet in a very simple application will make it possible to check if always using the HFXTAL will make the precision "good enough".

Best regards,

Edvin