This quick start will echo back characters typed into the terminal.
In this use case the USART will be configured with the following settings:
- Asynchronous mode
- 9600 Baudrate
- 8-bits, No Parity and one Stop Bit
- TX and RX enabled and connected to the Xplained Pro Embedded Debugger virtual COM port
Setup
Prerequisites
There are no special setup requirements for this use-case.
Code
Add to the main application source file, outside of any functions:
Copy-paste the following setup code to your user application:
void configure_usart(void)
{
#if(SAMR30E)
{
config_usart.baudrate = 9600;
config_usart.mux_setting = CDC_SERCOM_MUX_SETTING;
config_usart.pinmux_pad0 = CDC_SERCOM_PINMUX_PAD0;
config_usart.pinmux_pad1 = CDC_SERCOM_PINMUX_PAD1;
config_usart.pinmux_pad2 = CDC_SERCOM_PINMUX_PAD2;
config_usart.pinmux_pad3 = CDC_SERCOM_PINMUX_PAD3;
}
}
#else
{
config_usart.baudrate = 9600;
config_usart.mux_setting = EDBG_CDC_SERCOM_MUX_SETTING;
config_usart.pinmux_pad0 = EDBG_CDC_SERCOM_PINMUX_PAD0;
config_usart.pinmux_pad1 = EDBG_CDC_SERCOM_PINMUX_PAD1;
config_usart.pinmux_pad2 = EDBG_CDC_SERCOM_PINMUX_PAD2;
config_usart.pinmux_pad3 = EDBG_CDC_SERCOM_PINMUX_PAD3;
EDBG_CDC_MODULE, &config_usart) !=
STATUS_OK) {
}
}
#endif
}
Add to user application initialization (typically the start of main()
):
Workflow
- Create a module software instance structure for the USART module to store the USART driver state while it is in use.
- Note
- This should never go out of scope as long as the module is in use. In most cases, this should be global.
- Configure the USART module.
- Create a USART module configuration struct, which can be filled out to adjust the configuration of a physical USART peripheral.
- Initialize the USART configuration struct with the module's default values.
- Note
- This should always be performed before using the configuration struct to ensure that all values are initialized to known default settings.
- Alter the USART settings to configure the physical pinout, baudrate, and other relevant parameters.
#if(SAMR30E)
{
config_usart.baudrate = 9600;
config_usart.mux_setting = CDC_SERCOM_MUX_SETTING;
config_usart.pinmux_pad0 = CDC_SERCOM_PINMUX_PAD0;
config_usart.pinmux_pad1 = CDC_SERCOM_PINMUX_PAD1;
config_usart.pinmux_pad2 = CDC_SERCOM_PINMUX_PAD2;
config_usart.pinmux_pad3 = CDC_SERCOM_PINMUX_PAD3;
- Configure the USART module with the desired settings, retrying while the driver is busy until the configuration is stressfully set.
- Enable the USART module.
Use Case
Code
Copy-paste the following code to your user application:
uint8_t string[] = "Hello World!\r\n";
uint16_t temp;
while (true) {
}
}
}
Workflow
- Send a string to the USART to show the demo is running, blocking until all characters have been sent.
uint8_t string[] = "Hello World!\r\n";
- Enter an infinite loop to continuously echo received values on the USART.
- Perform a blocking read of the USART, storing the received character into the previously declared temporary variable.
- Echo the received variable back to the USART via a blocking write.