Baro Sensor
In an effort to avoid cleaning for a bit, and because a friend inquired about this blog, I decided to write this short post.
In the last post, I hadn’t yet received the barometric pressure sensor. It has since been installed and I wrote some code to talk to it. Unfortunately, while I’m pretty sure the SPI communications are correct, I’m getting bad data out of it. Pressures and temperatures after calibration are no good. Without the data sheet, these will be meaningless, but here’s an example of what I’m seeing:
| RawT | 8730660 |
|---|---|
| RawP | 8712672 |
| dT | 255012 |
| off | 5099102517 |
| sens | 2820650753 |
| Temp | 2008 |
| Press | 2020 |
I sent an inquiry to Measurement Specialties, and they responded that they agreed the values didn’t look right, but they didn’t reply to my follow-up, and I got distracted with other things.
Well, that’s enough procrastinating. Back to cleaning house!
So when is the launch? I put up a failed attempt last year (nearspaceballoon.blogspot.com) and this year I’m going to do it right. Our parts list looks pretty similar:
-SAM3S-EK
-GM862 cellular module
-Xtend 900 radios
-TMP122 temp sensor
-MS5801-01BA pressure sensor
-GS407 GPS module
-uM-FPU co-processor (for easy NMEA string parsing and calculations)
Most of my firmware is written, except the radio and pressure sensor drivers. I’d be happy to share with you. If everything goes well I’ll be launching in July somewhere near Spokane, WA.