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##

# 2.110.26 SERCOMx_USART_ReadThresholdSet Function

## C

    /* x = SERCOM instance number */

    /* Ring buffer mode */

    void SERCOMx_USART_ReadThresholdSet(uint32_t nBytesThreshold)

## Summary

This API allows the application to set a threshold level on the number of bytes of data available in the receive buffer

## Description

This API allows the application to set a threshold level on the number of bytes of data available in the receive buffer. Once the threshold is reached a notification is given to the application if it is enabled.

## Precondition

SERCOMx_USART_Initialize must have been called for the associated SERCOM_USART instance.

## Parameters

Param | Description
--- | ---
nBytesThreshold | Threshold value for number of bytes available in the receivebuffer after which a notification must be given

## Returns

None

## Example

    uint8_t rxBuffer[50];
    uint32_t nBytes;

    void usartReadEventHandler(SERCOM_USART_EVENT event, uintptr_t context )
    {
        uint32_t nBytesAvailable = 0;

        if (event == SERCOM_USART_EVENT_READ_THRESHOLD_REACHED)
        {
            // Receiver should have the thershold number of bytes in the ring buffer
            nBytesAvailable = SERCOM0_USART_ReadCountGet();

            nBytesRead += SERCOM0_USART_Read((uint8_t*)&rxBuffer[nBytesRead], nBytesAvailable);
        }
    }

    //----------------------------------------------------------//

    // Register a callback for read events
    SERCOM0_USART_ReadCallbackRegister(usartReadEventHandler, (uintptr_t) NULL);

    // Set a threshold value to receive a callback after every 10 characters are received
    SERCOM0_USART_ReadThresholdSet(10);

    // Enable RX event notifications
    SERCOM0_USART_ReadNotificationEnable(true, false);

## Remarks

None