nRF52840: can we use UART0 with interrupt api and UART1 with async api?

[Alaganraj]

Hi,

We are using nRF52840 for our project. we need two UARTs

UART0 - for BLE

UART1 - for communicating with SOC 

Zephyr RTOS supports following API for UART.

Async UART API
Interrupt-driven UART API 
Polling UART API

Throughput measurement:

Setup:

nRF52840 UART0 and UART1 connected to ubuntu host using FTDI interface (USB to serial)

We implemented interrupt-driven api based application to send/receive data to/from ubuntu. 

We are seeing throughput of max 11.8KBps rate at Baud rate 1Mbps, which is very low. 

Rx receive only 1 byte per interrupt but Tx transmits 32 byte per interrupt.

hope, using Async api will improve the throughput as it uses DMA.

we are more inclined to use interrupt driven api because we are using hci_uart sample program for BLE controller, which is implemented using interrupt-driven api.

request you to clarify following queries

1. Can we use interrupt-driven api  for UART0 and Async API for UART1 in same application?

2. Can we configure the RX FIFO length? ie) Is it possible for receive more than 1 byte per interrupt in interrupt-driven api?

Thanks in advance

Alaganraj

[Sigurd]

Hi,

1. Can we use interrupt-driven api  for UART0 and Async API for UART1 in same application?

Yes, some relevant configs:

CONFIG_SERIAL=y


CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_UART_ASYNC_API=y

CONFIG_UART_0_INTERRUPT_DRIVEN=y

CONFIG_UART_1_INTERRUPT_DRIVEN=n
CONFIG_UART_1_ASYNC=y

ie) Is it possible for receive more than 1 byte per interrupt in interrupt-driven api?

No.

[Alaganraj]

Hi Sigurd,

Thank you for prompt response. Let me try this out and get back to you.