UART and UARTE peripherals

[danmcb]

I've asked before about these two peripherals, the way they are presented is a little confusing.

I understand that UARTE has DMA possibilities, UART doesn't. Also that in effect there is only one UART on the chip.

In the case that I just want a very simple UART for debugging purposes, with the minimum of config and so on - what is recommended?

Is UARTE a superset of UART, and can be setup as a simple peripheral without using the DMA stuff?

Is it recommended in new designs to use UARTE over UART in new designs? I ask because much UART documentation and driver code seems to be in legacy status now.

Thanks for clarifying.

[mrono]

The way I look at UART/UARTE is that there is only one peripheral with two different access methods.

If you access the peripheral using UARTE-> -registers, DMA will be enabled automatically. And similarly if you use UART-> -registers, DMA will be disabled.

Both should be fairly equal in terms of complexity for a simple debug uart.

[danmcb]

there is this though - a flag to turn off DMA use.

/**@brief Structure for UART configuration. */

typedef struct

{

    uint32_t            pseltxd;            ///< TXD pin number.

    uint32_t            pselrxd;            ///< RXD pin number.

    uint32_t            pselcts;            ///< CTS pin number.

    uint32_t            pselrts;            ///< RTS pin number.

    void *              p_context;          ///< Context passed to interrupt handler.

    nrf_uart_hwfc_t     hwfc;               ///< Flow control configuration.

    nrf_uart_parity_t   parity;             ///< Parity configuration.

    nrf_uart_baudrate_t baudrate;           ///< Baudrate.

    uint8_t             interrupt_priority; ///< Interrupt priority.

#if defined(NRF_DRV_UART_WITH_UARTE) && defined(NRF_DRV_UART_WITH_UART)

    bool                use_easy_dma;

#endif

} nrf_drv_uart_config_t;

[mrono]

I think that is just the Nordic uart driver's way of choosing either uart or uarte.

[danmcb]

no, there are separate files, typedefs, everything, for UART and UARTE.

[Simonr]

Hi

The file you refer to is the legacy nrf_drv_uart.c/.h files, which if from before the UART and UARTE drivers had separate files. In the nrfx drivers we have separate files for UART and UARTE, and it works similar to what Markku describes, where the UARTE and UART is just the peripheral with and without EasyDMA. We generally recommend using the UARTE with EasyDMA as there isn't much extra setup compared to the simple UART, but you're free to use the basic UART if you prefer that.

Best regards,

Simon