Introduction

I built this small TTN-Node (TheThingsNetwork-Node) to measure temperature and humidity with a precise DHT22-Sensor. The used microcontroller is a ATmEGA 328P-AU and the LoRa-Transceiver for transmitting to the Network is a RFM95W. The Node is fully assembled and comes with a suitable enclosure as you can see in the picture.

The board needs to be in the range of an TTN-Gateway (most likely you know that). Information about The Things Network you can find here.

The Hardware

The board was desined with Autodesk Eagle, you find the Eagle-files here, also a PDF from the Schematic and the board-layout.

Power:

Use the Micro-USB-Port for powering the node. This port is only for power, no connection to the microcontroller over this port is possible, use instead the FTDI-Port.

FTDI-Port:

If you want use the build-in firmware and want to configure your TTN-Node with the credentials (DevEUI, AppEUI and AppKey), you must use a FTDI-Adapter (USB to serial) and connect it to the FTDI-Port as shown in the picture. Then you can use the Serial Monitor of the Arduino IDE to configure. (A more detailed desciption on github is linked under documents under this text). For uploading own sketches you also use the FTDI-Adapter (set the board in Arduino IDE to "Arudino Duelmilanavo 328p"). If you don´t own a FTDI-Adapter you can buy one for less money. Just google for it. Important: Use one you can configure to use 3.3V and use this 3.3V-setting when connecting to the TTN-Node.

ISCP-Port:

If you want to burn another bootloader you will find a ISCP-Port on the PCB. If you want to use the ISCP-Port you first must change the default setting of the two DIP-Switches.

Using ISCP: Put the 3 switches from S2 (left) to "On", and the 3 switches from S1to (right) "off" Normal Operating: Put the 3 switches form S1 (right) to "On", and the 3 switches from S2 (left) to "off"

Following the links under "Specs and Docs" you will find much more information on github:

• Arduino Sketch

• Eagle Design-Files

• How to visualize the data on myDevices Cayenne

• Useful link if you want to visualize with the Node Red, influxdb and Grafana