[nRF Connect SDK] Async UART Rx loss

[Tim Hwang]

Target nRF52832(nrf52dk_nrf52832)
SDK NCS v1.9.1
Base source: C:\Users\user\ncs\v1.9.1\nrf\samples\bluetooth\peripheral_hids_keyboard
I add uart implementation from following source.
C:\Users\user\ncs\v1.9.1\nrf\samples\peripheral\lpuart

baud rate: 921600
flow control: hw

I found some of data are missing.

UART Rx buffer size: 128
----------------------------------
(last received. 122)
00> E: received 122
----------------------------------
(0123456789 <- 10 bytes was sent.)

00> evt->type 2 (UART_RX_RDY)
00> E: evt->data.rx.len 6 <- actually 6 bytes received. 4 bytes are lost.
00>
00> E: evt->data.rx.offset 122
00>
00> E: received 128
00> evt->type 4 (UART_RX_BUF_RELEASED)
00> evt->type 3 (UART_RX_BUF_REQUEST)
----------------------------------
Finally 4 bytes are lost.

I review doc regarding uart, but no loss issue was found.
academy.nordicsemi.com/.../
Do you have any idea? I'm afraid that flow control is working properly.

[Tim Hwang]

static void uart_callback(const struct device *dev,
			  struct uart_event *evt,
			  void *user_data)
{
	struct device *uart = user_data;
	int err;

	printk("evt->type %d\n", evt->type);

	switch (evt->type) {
	case UART_TX_DONE:
		//LOG_INF("Tx sent %d bytes", evt->data.tx.len);
		break;

	case UART_TX_ABORTED:
		//LOG_ERR("Tx aborted");
		break;

	case UART_RX_RDY:
		recv += evt->data.rx.len;
		LOG_ERR("evt->data.rx.len %d", evt->data.rx.len);
		LOG_ERR("evt->data.rx.offset %d", evt->data.rx.offset);
		LOG_ERR("recv2 %d", recv);
		break;

	case UART_RX_BUF_REQUEST:
	{
		uint8_t *buf;
		//LOG_ERR("UART_RX_BUF_REQUEST");

		err = k_mem_slab_alloc(&uart_slab, (void **)&buf, K_NO_WAIT);
		__ASSERT(err == 0, "Failed to allocate slab");

		err = uart_rx_buf_rsp(uart, buf, BUF_SIZE);
		__ASSERT(err == 0, "Failed to provide new buffer");
		break;
	}

	case UART_RX_BUF_RELEASED:
		//LOG_ERR("UART_RX_BUF_RELEASED");
		k_mem_slab_free(&uart_slab, (void **)&evt->data.rx_buf.buf);
		break;

	case UART_RX_DISABLED:
		//LOG_ERR("UART_RX_DISABLED");
		{
		uint8_t *buf;
		err = k_mem_slab_alloc(&uart_slab, (void **)&buf, K_NO_WAIT);
		__ASSERT(err == 0, "Failed to alloc slab");

		err = uart_rx_enable(uart, buf, BUF_SIZE, SYS_FOREVER_MS/*UART_WAIT_FOR_RX*/);
		__ASSERT(err == 0, "Failed to enable RX");
		}
		break;

	case UART_RX_STOPPED:
		break;
	}
}

static void uart_init(void)
{
	static const struct device *lpuart;
	lpuart = device_get_binding("UART_0");
	int err;
	uint8_t *buf;

	if (lpuart == NULL) {
        printk("Cannot initialize UART0 device\n");
    }
	else {
	   printk("Getting done UART_0\n");

		err = k_mem_slab_alloc(&uart_slab, (void **)&buf, K_NO_WAIT);
		__ASSERT(err == 0, "Failed to alloc slab");

		err = uart_callback_set(lpuart, uart_callback, (void *)lpuart);
		__ASSERT(err == 0, "Failed to set callback");

		err = uart_rx_enable(lpuart, buf, BUF_SIZE, 10000/*UART_WAIT_FOR_RX*/);
		__ASSERT(err == 0, "Failed to enable RX");
	}
}

[Tim Hwang]

nrf52dk_nrf52832.overlay

&uart0 {
status = "okay";
tx-pin = <14>;
rx-pin = <13>;
rts-pin = <17>;
cts-pin = <16>;
current-speed = <921600>;
hw-flow-control;
};