UART Device Driver (RFD900)

[StanleyTang17]

Description

What was completed, changed, or updated?

Added a generic UART device driver for communication with RFD900 and other UART devices.

• Receive UART data in DMA mode and save them in an internal circular buffer that the user can read from.
• Transmit data in polling mode instead of DMA mode to avoid taking up too many DMA channels.

Why was this done (if applicable)?

This driver is mainly used to receive UART data reliably without dropping any bytes, which is achieved with the DMA RX + internal buffer combo. Since STM32 HAL does not have an internal buffer aside from DMA, there is a risk of dropping data if we don't call HAL receive in time. Using this driver, we can automatically store the data we receive in our own internal buffer for later. As long as we read from our internal buffer fast enough, we shouldn't be droppping any bytes.

Testing

What manual tests were used to validate the code?

1. Wire up two uart channels together and verify that they can transmit to and receive from each other.

void ping_pong_test()
{
	const uint16_t buf_size = UARTDevice::BUFFER_SIZE;
	uint8_t buf[buf_size];
	uint16_t data_size = 0;

	const uint8_t max_test_iterations = 5;

	const char* ping_msg = "Ping";
	const char* pong_msg = "Pong";

	for (uint8_t test_iterations = 0; test_iterations < max_test_iterations; test_iterations++) {
		myprintf("Test Iteration #%d\r\n", test_iterations + 1);

		// Send ping
		p_uart_dev1->transmit((uint8_t*)ping_msg, strlen(ping_msg));
		myprintf("UART Device 1: ping sent.\r\n");

		// Receive ping
		data_size = 0;
		while (data_size == 0) {
			data_size = p_uart_dev2->getAvailDataSize();
			osDelay(10);
		}

		memset(buf, 0, buf_size);
		p_uart_dev2->read(buf, data_size);
		if (strcmp((char*)buf, ping_msg) == 0) {
			myprintf("UART Device 2: ping received.\r\n");
		} else {
			myprintf("UART Device 2: invalid message received.\r\n");
			break;
		}

		// Send pong
		p_uart_dev2->transmit((uint8_t*)pong_msg, strlen(pong_msg));
		myprintf("UART Device 2: pong sent.\r\n");

		// Receive pong 
		data_size = 0;
		while (data_size == 0) {
			data_size = p_uart_dev1->getAvailDataSize();
			osDelay(10);
		}

		memset(buf, 0, buf_size);
		p_uart_dev1->read(buf, data_size);
		if (strcmp((char*)buf, pong_msg) == 0) {
			myprintf("UART Device 1: pong received.\r\n");
		} else {
			myprintf("UART Device 1: invalid message received.\r\n");
			break;
		}
	}
}

Test results:

2. The previous test but done in ZP3.5 to make sure it's properly integrated in ZP3.5.
3. Verify that it can receive data from an actual RFD900. (Optional?).

What unit tests were used to validate the code?

Circular buffer unit tests to verify functionality.

Documentation

Milestone number and name: Fixed Wing Milestone 2

Link to Asana task: https://app.asana.com/0/1203458353737758/board

Link to Confluence documentation: https://uwarg-docs.atlassian.net/wiki/spaces/ZP/pages/2251980914/RDF+900

Reminders

• Integration testing

• Update confluence documentation

• Add reviewers to the PR

• Mention the PR in the appropriate discord channel

[Chrisc110]

Looks good to me, before I approve can you just also attach a screenshot of the successful unit tests?

[StanleyTang17]

Looks good to me, before I approve can you just also attach a screenshot of the successful unit tests?

Done

[SnackkOverflowError]

lgtm