# 12 Testing and qualification
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## 12.1 Test hardware
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The ExpressLink testing and qualification process requires a Raspberry Pi 4 single board computer and a hardware harness providing the following connections: 

<a name="elpg-figure7"></a>![Figure 7 - RaspberryPi 4 I/O connections](http://docs.aws.amazon.com/iot-expresslink/archive/v1.1.2/programmersguide/images/image7.png)


The ExpressLink candidate will be attached to the GPIO header of the PI using the following pins.


**Table 7 - Test I/O pin assignments**  

| ExpressLink function | GPIO Pin Number | 
| --- | --- | 
| Command TX (Transmit from ExpressLink to Host) | GPIO 15 | 
| Command RX (Receive from Host to ExpressLink) | GPIO 14 | 
| Reset | GPIO 23 | 
| Event | GPIO 27 | 
| Wake | GPIO 22 | 

## 12.2 Test software
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A test suite is provided by the AWS FreeRTOS service team to perform the ExpressLink Qualification, a program managed by the AWS Partner Network team.