I am embarking on a journey to build a mini arduino altimeter for my estes rocket. There are a few tutorials out there, like this one, but instead of having the altitude output of a bubble display, I want it to log the data onto a SD card to be read by a computer later.
I was hoping if the members of this community can help me create a plan for building my own tiny altimeter. This is also my first time working with Arduino (I have tons of experience working with Raspberry Pi, have built model rockets - w/o flight computers - and I am a software engineer by profession) and doing any sort of soldering.
You would connect the Pro Mini and the pressure sensor as you would any I2C sensor (Adafruit has many excellent tutorials), download the Adafruit library for that sensor and compile and run one of the examples.
To record on an SD card, the simplest approach is to route the serial output to the incredibly useful SparkFun Openlog, which is about the size of the altimeter module.
It is conceivable that there is room in the OpenLog memory (which uses the same processor as the Pro Mini) to accommodate the sensor code, in which case you don't need the Pro Mini.
I think I would use something like an esp32 board and store the readings in its onboard flash. No need for an SD card. You can program it so it outputs its readings to uart when you connect it to a host computer, and record altimeter readings when you set it into flight mode.
Interesting point about replacing the Pro Mini with the memory in the OpenLog chip. When you say it is conceivable, are you sure about this :D. Since this is my first time working with arduino, I would like to stay simple, but I see what you are getting at here.
I am quite sure that it is conceivable. I am not certain that the code could be made to fit, but similar mods have been made to OpenLog and posted on the web.
There is also the new OpenLog Artemis. I have no experience with it, but it may work out of the box with that sensor.
I saw that one, but it is costly. I like the Mini/OpenLog approach because they are cheap.
I am not certain that the code could be made to fit
I feel like if the code could fit on a Pro Mini, then it should fit on an OpenLog since I can add whatever size microsd I want, right? I would be shocked if the code was over 1GB.
Can I solder the altimeter sensor directly to OpenLog and the battery as well?
I'm talking about the 32K bytes of processor instruction code memory in the ATmega328 processor, common to the Pro Mini and the OpenLog.
You can connect the OpenLog and the sensor by soldered wire connections, but the I2C communication pins for the sensor aren't brought out on the OpenLog PCB. You would have to make connections directly to the processor pins.