IMU-II & FTDI board connected and TX'ing IMU-II soldered a little better Calibrating the Uchusen IMU-II Backup IMU soldered to 6-pin header Uchusen's amazing (?) soldering area

Soldering, hooking up and calibrating this new 9-DOF IMU has been taking up most of my time this week. This IMU will allow our future craft to know which direction it is pointing in, and where it is heading if there are any changes in direction. Tied to the GPS (still stuck in the United States Postal Service customs hold in NYC since 3 weeks now - never use these USPS guys), we’ll know where we are, what time it is, where we’re pointed and where we’re heading. It will also help to be able to continue tracking the craft even when out of GPS range. Not bad for a start!

  • Kicked off with the first 9 degrees-of-freedom (or “DOF”) IMU-I bought a while back and that for some reason couldn’t get to work. Managed to make two solder blobs on both the 1V8 and SCL holes… don’t know if the connections ended up being any good, but will find out when I revisit this backup IMU.
  • Then moved on to the piece de resistance IMU-II which just came in a few days ago. Although abt four times the size of the first one, soldering went ok, and it was easy to connect up to the FTDI breakout board and USB. Yaw pitch and roll data flowed through COM13 the very first time! Unbelievable but true.
  • Next stop calibration: every one of the 9 axes of freedom needs a min and a max. This allows fine-tuning of the raw data coming off the sensors and was really tricky, but it worked. The result was still non-zero as you can see on the image, but it’s close enough for now…
Trying to work this new IMU-on-a-chip unit into my Arduino breadboard, but ye spirits of serial comms were just not in the mood today. Setup the Python libraries that were kindly provided for visualisation, got all the wires up ok, but I think this is really one of those times when you realise the answer lies in diving into those chip specs. Digging a little deeper, apparently the accelerometer etc are switched off by default, and need to be set in the registry file.
Problem is, going through the Arduino code provided shows various sensor data being averaged and fused together to provide a coherent output. So wrong place then. I even got the dummy “yes you have the thing switched on” line that pops up on the serial monitor at 115k baud. Tried to focus just on the LSM303DLM accelerometer libraries, which are fairly straightforward cpp/h files with a bunch of examples that run off those, but guess it was the end of the day (or I didn’t read the chip parameter specs closely) and I ended up running the serial check example. When nothing came through, just called it a day.
Sometimes ye spirits of serial comms don’t smile, and those days you just have to give it your best and convince yourself with “I learnt something today”. Tomorrow is a new day and another chance at cracking the mystery of the IMU-on-a-chip!

Trying to work this new IMU-on-a-chip unit into my Arduino breadboard, but ye spirits of serial comms were just not in the mood today. Setup the Python libraries that were kindly provided for visualisation, got all the wires up ok, but I think this is really one of those times when you realise the answer lies in diving into those chip specs. Digging a little deeper, apparently the accelerometer etc are switched off by default, and need to be set in the registry file.

Problem is, going through the Arduino code provided shows various sensor data being averaged and fused together to provide a coherent output. So wrong place then. I even got the dummy “yes you have the thing switched on” line that pops up on the serial monitor at 115k baud. Tried to focus just on the LSM303DLM accelerometer libraries, which are fairly straightforward cpp/h files with a bunch of examples that run off those, but guess it was the end of the day (or I didn’t read the chip parameter specs closely) and I ended up running the serial check example. When nothing came through, just called it a day.

Sometimes ye spirits of serial comms don’t smile, and those days you just have to give it your best and convince yourself with “I learnt something today”. Tomorrow is a new day and another chance at cracking the mystery of the IMU-on-a-chip!

Solar-powered arduino on workbench Panel view with arduino power feed Solar panel closeup!

Just finished my first solar-powered #Arduino setup, no more relying on USBs and other non-space-like power for Uchusen projects! From now on, no light, no project. Simple as that. First picture shows the humble workbench with arduino uno and solar panel side-to-side. Below, snapshots of the finished backside of the panel that feeds the chip, and a closeup of the panel.

The 3W solar panel came without its wiring so had to go out but none available nearby, so kind of (ahem) tweaked standard electronics kit wires to do the trick. Added in the DC-DC converter and battery into the mix, then plugged into the 5V Arduino. The panel wasn’t exactly the most sensitive beast around, and there were a number of issues hooking the whole thing up without it all falling apart when you pick up the unit. But now things seem to be running smoothly with the battery still supplying the microprocessor with no hiccups, 3h+ after switching off the light source. So far so good!

Note to self: and now for a little XBee magic so I can get rid of the mini USB cable ritual for good… but that will have to wait a little longer. More exciting news to come next week.