RE: BUS fault/kerel panic on NUS

allenboon — Fri, 23 Dec 2022 01:53:00 GMT

Hello Edvin,

I have solved this issue yesterday, it seems a buffer overflow issue. But, the function still have strange condition.

Are you actually receiving your data from a uart input? (I am asking since you are using a dongle, which doesn't have anything connected to the UART pins by default.)

Yes, because I do not have enough time to add usb function to central uart code. So, I connect another UART converter(a CP210x UART brigge) to dongle UART pins. It can works transfer & read data.

How long are the packets that you are trying to send? Is it always less than 20 bytes?

My function only need transfer 8 - 9 bytes (include C/R character).

I tried use some log. Then, I found issue like if host uart send 9 bytes. central_uart uart_cb function only recieved 8 bytes.

Because FW cannot detect C/R character, so it do not send data to peripheral (I mean below source code in uart_cb function)

	case UART_RX_RDY:
		//LOG_INF("UART_RX_RDY");
		buf = CONTAINER_OF(evt->data.rx.buf, struct uart_data_t, data);
		buf->len += evt->data.rx.len;
		buf_release = false;
		LOG_HEXDUMP_INF(buf->data, buf->len, "uart rx");
		if (buf->len == UART_BUF_SIZE) {
			k_fifo_put(&fifo_uart_rx_data, buf);
		} else if ((evt->data.rx.buf[buf->len - 1] == '\n') ||
			  (evt->data.rx.buf[buf->len - 1] == '\r')) {
			k_fifo_put(&fifo_uart_rx_data, buf);
			current_buf = evt->data.rx.buf;
			buf_release = true;
			uart_rx_disable(uart);
		}

		break;

So, my host do not know data loss condition and host have retry mechanism. The uart_cb rx fifo will increase more and more. At the end, the fifo will overflow, more than the prj setting CONFIG_UART_0_NRF_TX_BUFFER_SIZE value.

Then I tried to set CONFIG_UART_0_NRF_TX_BUFFER_SIZE is multiple of transfer data bytes. It still have loss data condition, but the retry mechanism works.

In the meanwhile. Do I need anything other to reproduce your issue?

I have solved this issue, I think you do not need to reproduce issue. But, I do not know why uart_cb will have loss data issue. if you any other suggestions, please feel free to provide them.

Finally, thanks your reply. Have a nice Holiday Season!!

Allen.

RE: BUS fault/kerel panic on NUS

Edvin — Thu, 22 Dec 2022 12:37:20 GMT

Hello Allen,

What, in particular makes you think it is related to the issue in your link? And did you try applying the fix that was proposed in that ticket?

Are you actually receiving your data from a uart input? (I am asking since you are using a dongle, which doesn't have anything connected to the UART pins by default.)

How long are the packets that you are trying to send? Is it always less than 20 bytes? Or did you increase the MTU size? Sorry, your project probably holds answer to most of my questions, but I am on my way out of the office, and we are really short staffed because of Holiday Season. I am sorry for the inconvenience, but we will be back to normal operation in January.

In the meanwhile. Do I need anything other to reproduce your issue? Did you try this using two DKs instead of a Dongle and a DK? The reason I ask is that we don't have any dongles with debuggers, so it is a bit more difficult to debug on those.

Best regards,

Edvin