Communication between nrf52840 and nrf9160 on nrf9160DK over lpuart

[Youssef Elbattah]

Hello,

I'm attempting to establish communication between an nRF52840 and an nRF9160 on the nRF9160DK using LPUART. Initially, I tried using the interrupt-driven mode, but the uart_fifo_fill function only sends the packet once and then sends 0 bytes on both sides.

Next, I switched to the async mode API for LPUART by disabling the interrupt-driven mode. However, when I attempt to use uart_tx, it returns EBUSY.

Best Regards

Youssef

[Einar Thorsrud]

Hi,

That is a good point. There are a couple of other reasons you might get this as well. The simplest in that case is to check with a debugger and backtrack why you got the UART_RX_DISABLED event. If you use UARTE, the relevant implementation is in zephyr/drivers/serial/uart_nrfx_uarte.c. And you can set a breakpoint in notify_rx_disable() first to verify that it originates there. Then backtrack and see where notify_rx_disable() is called from, and so on.

[Youssef Elbattah]

Hi,

I have a question: how can I determine whether I'm using UARTE or UART? In my configuration, I have enabled UART1, not UARTE1.

Best regards,

Youssef

[Einar Thorsrud]

Hi Youssef,

My comment about UARTE was unessary. Async UART only makes sense with UARTE (as that is where you have DMA). So I expect you use that. You can check in the device tree file for your board, where most likely ouar uart1 is set to compatible with "nordic,nrf-uarte" (note the "e" in the end). But you can also just check with the debugger to see which driver you end up in to be sure (you should anyway do that to figure out the issue you are debugging now).

[Youssef Elbattah]

Hi Einar,

You're right, the buffer is being filled with 100 bytes, which I didn't expect.

How can I provide a new buffer each time the current one is filled?

Best regards,

Youssef

[Youssef Elbattah]

Hi Einar,

It works, but I'm experiencing an unexpected delay between receiving packets from the other chip.

For example, the nRF91 sends packets every 2000ms, but I receive them approximately every 10 seconds.

Best regards

Youssef