3. Hardware interactions

1. Identifying Ground points

By looking at the PCB, we can identify a few potential candidates for the Ground points:

In the following video, I demonstrate how we can use the digital multimeter in continuity mode to test the GND points

• we will be able to identify it when a "beep" sound is heard:

• Notice that there are only 2 portions of the PCB (refer to image below) that responded with a "beep" sound

• These 2 points will be the Ground points

Confirmed GND points:

2. Identifying UART pins (TX, RX, GND, 3.3V)

In the following video, I demonstrate how to identify the pins on the UART Interface using the digital multimeter:

The following outlines the characteristics of each pin:

1. TX: fluctuates from 2.5 to 3.3V

2. RX: fluctuates slightly before stabilizing at 3.3V

3. GND: drops and stabilizes at 0.00V

4. 3.3V: fluctuates slightly before stabilizing at 3.3V (more erratic fluctuation that RX)

3MB

IMG_5654.HEIC

Open

3MB

IMG_5654.HEIC

Open

3. Taking a closer look at TX+RX

In the following video, we focus on the voltage values of the TX and RX pins right after the router is powered ON:

4. UART pins layout