ATtiny84 LoRa – Frequently Asked Questions

I’ve had several mail with questions about my project. Even some have ordered the PCB and reproduced or extended my initial project. I like that very much, and please when you do, please send me an e-mail (with pictures) of your project and application.

What development environment are you using?

I use PlatformIO as development environment. It is an extension of the Atom editor/IDE. I use this one because it is like a professional IDE, where I have an overview of libraries, and Git integrated.
(https://platformio.org)

You will find no .ino file. You can use main.cpp as you base of your .ino file. Be sure to add the libraries from this project to your Arduino environment.

How do you upload the code to the ATtiny84?

I use the USBASP programmer (https://www.fischl.de/usbasp/).

You can use connectors/wires and a breadboard to program a single chip. However I use a 28-Pen DIP ZIF socket:

How long will the batteries last?

I do have some information on the batteries. It depends on the conditions like temperature and time between measurements. On all LoRa devices on batteries I measure and send every 5 minutes data. I do not use a brown out detector, so you have to know on what voltage it will stop sending data. The experience I have so far in oktober 2018:

What kind of LoRa activation do you use?

Can I decode the information FROM/on TTN network?

function Decoder(Data, port) {
var vccVoltage = (Data[0] << 8) | Data[1];
var temp = (Data[2] << 8) | Data[3];
var hum = (Data[4] << 8 ) | Data[5];

return {
vcc: vccVoltage / 1000,
temperature: temp / 100,
humidity: hum / 100,
};
}

byte[] byteData = Base64.getDecoder().decode(payload_raw);

// voltage level
int vccVoltage = (byteData[0] << 8) + toUnsignedInt(byteData[1]);
float vccVFl = vccVoltage/1000F;
vccVoltageStr = String.format("%.3f", vccVFl);

Can I USE the pressure?

Thanks to Kim, who tried to get my device working to measure pressure, we have found out that it is not possible at this moment. When you enable the pressure features (the code is already there) the compiled code is far to big to fit into the flash memory of the ATtiny84.
The reason for growing so big is that the sensor and thus software uses calibration data from the BME280 chip to calculate the real information. There are a few workarounds: Get the calibration data from the BME280 chip and send the raw data and then do the calculation on the (receiving) sever side. You have to bare in mind that every chip has its own calibration data. A other workaround is to use an other microcontroller. That is the path I’m walking on. I am switching to STM32L – chips (als SMD types). This will take a while, because I have to learn how to program them and make new prototypes.

== UPDATE ==
Rob has found example code at https://github.com/ClemensRiederer/TinyLoRa-BME280 from Clemens Riederer. He modified this code and was able to squeeze it into 8k memory (99% full). I was able to test this in the Arduino IDE, and it was working beautifully.

Any questions?

Please contact me through the comment on this or other pages. I will try to mail you back a soon as possible.