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# 1.9 FLEXCOM USART Flow Control

This example application shows how to use the FLEXCOM module in USART flow control mode.

## Description

This application configures FLEXCOM11 in non-blocking mode and FLEXCOM9 in blocking mode. FLEXCOM11 is used for data transmission and FLEXCOM9 is used for reception. The TX line of FLEXCOM11 is connected to the RX line of FLEXCOM9. The RTS line of FLEXCOM9 is connected to the CTS line of FLEXCOM11. FLEXCOM11 transmits 100 characters using interrupts. Application however simulates a slow receiver by inserting a delay after each character is read on FLEXCOM9. As a result, once the RX FIFO is full, the RTS line is de-asserted and transmitter (FLEXCOM11) stops sending the data. Eventually, when the receiver reads out sufficient number of bytes from the RX FIFO, such that the number of bytes in the FIFO goes below RXFTHRES2, the RTS line is again asserted and the transmitter continues sending the data. The demo application indicates success if the received data matches the transmitted data.

## Downloading and Building the Application

To clone or download this application from Github, go to the main page of this repository and then click Clone button to clone this repository or download as zip file. This content can also be downloaded using content manager by following these instructions.

Path of the application within the repository is apps/flexcom/usart/flexcom_usart_flow_control/firmware.

To build the application, refer to the following table and open the project using its IDE.

Project Name | Description
--- | ---
sam_a7g5_ek.X | MPLABX project for SAMA7G54 Evaluation Kit

## Setting Up AT91Bootstrap Loader

To load the application binary onto the target device, we need to use at91bootstrap loader. Refer to the at91bootstrap loader documentation for details on how to configure, build and run bootstrap loader project and use it to bootstrap the application binaries.

## Setting Up the Hardware

The following table shows the target hardware for the application projects.

Project Name | Description
--- | ---
sam_a7g5_ek.X | SAMA7G54 Evaluation Kit

### Setting Up SAMA7G5 Evaluation Kit

SETTING UP THE BOARD

- Connect the Debug USB port on the board to the computer using a micro USB cable
- Make connections as following:
  - Connect Mikrobus1, MOSI pin (F11_TXD) to mikroBUS2, SCL pin (F09_RXD)
  - Connect Mikrobus1, CS pin (F11_CTS) to mikroBUS2, INT pin (F09_RTS)

## Running the Application

1. Build the application using its IDE
2. LED is turned ON on success.

The following table provides the LED name:

Board | LED Name
--- | ---
SAMA7G54 Evaluation Kit | RGB_LED (Blue)