Skip to main content

GAGA-1: Working flight computer

And so after much preparation and the early success in getting RTTY transmission working I soldered everything onto the custom Arduino shield that forms the flight computer, plugged it in and... it just worked!

Here's the flight computer board connected to the Arduino. The biggest item is the Radiometrix NTX2 module with a small voltage divider below it which is used to set the frequencies for the 0 and 1 values. The antenna is connected to the SMA connector bottom left.

Just above the radio is the DS1821 temperature sensor that will measure internal capsule temperature. It has an associated pull up resistor. The external temperature sensor connects to the three pin header to the right of the radio (it too has a pull up resistor).

Here's a log of transmitted temperature data received via RTTY:
$$GAGA,24.0,Error: 0,
$$GAGA,24.0,Error: 0,
$$GAGA,24.0,Error: 0,
$$GAGA,24.0,Error: 0,
$$GAGA,24.0,Error: 0,
$$GAGA,23.9,Error: 0,
$$GAGA,23.9,Error::C'fwyZ
'/A,23.7,Error: 0,
$$GAGA,23.7,Error: 0,
$$GAGA,23.7,Error: 0x$$GAGA,23.8,23.3,
$$GAGA,23.7,22.9,
$$GAGA,23.7,22.6,
$$GAGA,23.7,22.6,
$$GAGA,23.7,29.8,
$$GAGA,23.7,29.7,
$$GAGA,23.7,27.6,
$$GAGA,23.7,26.1,
$$GAGA,23.7,25.0,
The first few lines of reports show the internal temperature (24.0C---yes, it's warm in the basement) and an error report (Error: 0) for the external temperature. The error was happening because I didn't have the sensor plugged in. I recently enhanced the code that handles the DS1821 sensor to report errors. Error 0 means that the sensor didn't respond.

The garbled output is because I was fiddling around with my radio. I then plugged the sensor in it started reading temperatures. The temperature peaked at 29.8C because I held the sensor in my hand.

Next steps are: a long distance test of transmission to make sure that's working correctly and install the GPS. With the GPS I'll be at the end of the long GAGA-1 road.

PS One final shot of the Arduino shield showing the painful leg bending required to fit in with the Arduino's silly pin spacing.

Comments

Popular posts from this blog

How to write a successful blog post

First, a quick clarification of 'successful'. In this instance, I mean a blog post that receives a large number of page views. For my, little blog the most successful post ever got almost 57,000 page views. Not a lot by some other standards, but I was pretty happy about it. Looking at the top 10 blog posts (by page views) on my site, I've tried to distill some wisdom about what made them successful. Your blog posting mileage may vary. 1. Avoid using the passive voice The Microsoft Word grammar checker has probably been telling you this for years, but the passive voice excludes the people involved in your blog post. And that includes you, the author, and the reader. By using personal pronouns like I, you and we, you will include the reader in your blog post. When I first started this blog I avoid using "I" because I thought I was being narcissistic. But we all like to read about other people, people help anchor a story in reality. Without people your bl

Your last name contains invalid characters

My last name is "Graham-Cumming". But here's a typical form response when I enter it: Does the web site have any idea how rude it is to claim that my last name contains invalid characters? Clearly not. What they actually meant is: our web site will not accept that hyphen in your last name. But do they say that? No, of course not. They decide to shove in my face the claim that there's something wrong with my name. There's nothing wrong with my name, just as there's nothing wrong with someone whose first name is Jean-Marie, or someone whose last name is O'Reilly. What is wrong is that way this is being handled. If the system can't cope with non-letters and spaces it needs to say that. How about the following error message: Our system is unable to process last names that contain non-letters, please replace them with spaces. Don't blame me for having a last name that your system doesn't like, whose fault is that? Saying "Your

The Elevator Button Problem

User interface design is hard. It's hard because people perceive apparently simple things very differently. For example, take a look at this interface to an elevator: From flickr Now imagine the following situation. You are on the third floor of this building and you wish to go to the tenth. The elevator is on the fifth floor and there's an indicator that tells you where it is. Which button do you press? Most people probably say: "press up" since they want to go up. Not long ago I watched someone do the opposite and questioned them about their behavior. They said: "well the elevator is on the fifth floor and I am on the third, so I want it to come down to me". Much can be learnt about the design of user interfaces by considering this, apparently, simple interface. If you think about the elevator button problem you'll find that something so simple has hidden depths. How do people learn about elevator calling? What's the right amount of