Connect the Transistor Circuit

Power down the Jetson and modify the breadboard circuit to include the transistor and its associated resistor. The schematic below shows the values calculated in the example worked through for this lab.

The LED will no longer connect directly to the GND rail. Instead connect it to the collector lead of the transistor. Connect R_B between the base of the transistor and a new rail with a jumper for the GPIO. Connect the emitter lead of the transistor to the ground rail.

Choose a GPIO pin

An earlier lesson on Interacting with Robotics Hardware included a concept on GPIO for the Jetson TX2. There is also a very nice illustration of the J21 header pinouts on JetsonHacks. For our example, we’ll use pin 18 in J21, there are others available for your use. Connect the jumper from the switch resistor to pin 18 on the J21 header to complete the circuit. When you power the Jetson back on, the light should be off. The final step is controlling pin 18 from the Jetson console!