Introducing Vayu

So, I have a HabDuino and that will be launched once I’ve got used to the whole set of logistics that are involved in HAB. I’d also like it to do something special rather then just send the normal telemetry back down to earth. I’m working on that.

Meanwhile, I have built Chris’s circuit board and christened it Vayu after the Indian god of the air and wind. It has an additional outboard regulator to take 1.5Volts up to 3.3Volts which is what the tracker circuit requires to run.

Vayu-1 HAB Payload

Vayu payload. Designed by Chris Stubbs.

The outboard regulator is actually a 3Volt to 5Volt version but you can substitute one of the SMD resistors to convert it. This isn’t ideal so I am currently re-designing the board with the regulator incorporated as well as a few other features I think would be useful. The regulator I have chosen is a Texas Instruments TPS61016 which is variable but will do the job with minimum component count.

One thing I wanted to do with Vayu’s telemetry is update the representation of time. The old code sent a string of numbers in HHMMSS format. I wanted it to send HH:MM:SS. Not being very experienced in ‘C’ programming, it took me one and a half days to research the problem and fix it. One of the issues was that I was using the Arduino IDE (Integrated Development Environment). Although this gives really easy access to program Arduinos with a language very similar to ‘C’, it isn’t fully compatible. I proved this by running a piece of code I’d written in Microsoft’s Visual C++ Express environment. It worked fine. As soon as I tried it in Arduino, no go. The character string was corrupted. Eventually, I found a complete different solution to the problem.

Another thing I wanted to do was make the telemetry useful in another way, not just for payload data. Chris showed me how to add another string of characters to the output.

$$$$VAYU, 97, 11:36:16, 51.452801, 00.176368, 15, 8, 1, 1, 2.83, 29*591F
Info at: http://www.projecthab.co.uk
$$$$VAYU, 98, 11:36:24, 51.452789, 00.176347, 15, 8, 1, 1, 2.87, 29*5E56
Info at: http://www.projecthab.co.uk

This is what the telemetry looks like now. As you can see, the time value near the beginning of the string includes colons to read easier and the telemetry string is interspersed with the address of this website. Hopefully, new enthusiasts will find this and use this site for reference, or at least a pointer to the UKHAS website which has a mound of info for HABers.

Hopefully, Vayu will fly soon. I am just awaiting funds for helium and a few other parts. Rest assured, I will write it up here when the time comes.


Steve Smith


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