Happy bunny

I've actually managed to get something done! OK it's nothing major, but I feel I've accomplished something. Something I haven't felt for a long time, so I'm a happy bunny. All I've done is added three buttons; up, down and home, along with adjustable end stops and home position to my bit banging servo code. I also upped the refresh rate to about 80Hz, from previous experience. I can substitute an EDF and could set the home position to be just below the point where the whole thing gets light on it's feet.

But I need to close the loop, so will dig out the ultrasonic rangers and try remember how to setup the ADC to read the range signal(s). I know, it's going to very crude...

Haven't had any photos recently, so thought I'd change that:

Microchip ICD2, my own dev board and standard servo.

ICD2 sorted (& plan B?)

Got it working last night by uninstalling MPLAB 8.6 and MPLAB X, then deleting the microchip folder. Installed 8.63 and X again, went through the driver installation and it connected!

So now I can mod my bit banging servo code for controlling an EDF.

But wait... thinking about it last night, there's no point doing all the low level stuff in the uC, that's just going to delay things even further. I need to use an external servo controller that I just talk to over serial comms. It takes a lot of overhead away from the main processor and makes servicing each task a lot simpler. Sound like a plan?

ICD2 is OK

Plugged it in, had to install drivers, but MPLAB connected to it fine.

Is it a Win7 problem?

Still no luck

Last night, I tried reinstalling ICD2 drivers, which didn't work. Then I downloaded and installed MPLAB X (Beta), no change. I can only assume my ICD2 died since I last used it!? Then I got bored so went and watched four or five episodes of The Big Bang Theory (thanks for the loan, Gary).

I'm going to take the ICD2 to work today and try it on my machine there.

Ardunio or PIC - Action Priority Matrix

I remembered this:

I don't want the tool to be a major project, unless it needs to be. Arduino's looking good!

Arduino or PIC?

A dilemma: what should I use? Should I buy into the ready-made hardware, tons of examples and accessories of the Arduino or do I stick with the more powerful/flexible PIC, which I've used before, which has a rich selection of peripherals and can make a smaller, neater end solution, but needs a lot more effort to get going?

The trouble is it's been a while since I did any serious PIC work and I'm attracted to the quick and easy Arduino. But I'm also not sure the Arduino will be up to scratch, with respect to I/O, peripherals and physical size (I could get a Nano?) and I'd have to learn a new platform.

So if I go for an Arduino, will I have to re-do everything in a PIC solution later? Should I go straight for a PIC solution, but with the extra time and effort?

I don't know. The Arduino does look like a quick solution...

Arduino website
Microchip PIC website

I had a little time!

A couple of weeks ago I managed to get some time (at a SHDC meet) to hack together some bit-banging code on a PIC to control a RC servo. This crude code, in theory, will allow me to control the servos for the landing gear, nacelle steering and of course the EDF thrust.

I had a little time over Christmas to discover my planned landing gear redesign was halted by my inability to mill a tidy slot in some aluminium channel with my tiny little lathe/mill combo. I need to come up with a simpler mechanism, get the gear done and put some kind of external skin on the airframe, then I can get to the control system!

Joost doon't 'ave the poower!

I made the adapter cable with the Deans connectors (cut off the end of the umbilical) and 4mm bullets fitted to mate with the Li-Po. I didn't know how charged the battery was, but I had to try it...

With just the battery (no extra weights) I powered up and "hovered" for a minute or so; all 3 EDFs running and plenty of power. I then added the 2 blocks of metal again. These are just bits I've been using to help in the construction so far, as weights or a square-edge. So powering again, it got off the ground but was obviously loaded. Second attempt and it just got off the ground and I hit max on the controller. I backed off, then tried again - now barely lifting. I took off the heavier block and re-tried - only slightly better. The battery must be dead! As I said; I don't know what the state of charge was beforehand and the charger hasn't arrived yet...

Disheartened by the sub-60 second runtime, I was thinking the battery couldn't have been charged. I wasn't expecting much, maybe 2 or 3 minutes. I also thought I should check and quantify the "other stuff", so went off to weigh the 2 blocks. They were a lot heavier than I thought: the larger block of aluminium was 335g and the smaller stainless steel block was 414g! For comparison, the battery is 408g (listed as 412g). That made me feel a little better; I'd added a lot more than necessary, an additional 759g (1.65lb for those working in old money). So fingers-crossed; if I can keep the weight of all that "other stuff" down and with a fully charged battery, it might just work... for a couple of minutes.

More parts: sensors and transceivers

Thanks to the guys at Sparkfun I'm now the proud owner of three Maxbotix LV-EZ0 ultrasonic range finders and a pair of nRF2401A transceivers with trace antennas. Now the only thing stopping me is time (and perhaps my coding skills) as I have all the main components I need to get things flying, but between work, studies and family my spare time is limited. I ask anyone following this to please be patient, and keep sending words of encouragement!

Follow the video from the previous post on YouTube as it links to some other interesting videos.

I'm going to attempt to finish the tail this week and start work on the control system.

L/G rework and accelerometers

I've been feeling off-colour this week so haven't got much done. I stripped a lot of the L/G from the airframe because I wasn't happy with it. I have thought of a way around the issues and will try to implement them next. This will give me a tidier, stronger end result.

I also dug out my Dimension Engineering DE-ACCM3D 3-axis accelerometer that I'd bought for a previous project and never got round to using. I hooked it up to my MiniLab 1008 (USB DAQ device) to re-familiarise myself with it. The DE-ACCM3D works fine but I seemed to be getting really slow, crappy resolution from MiniLab. I'm sure it was OK before...

System Block Diagram

Here's my first draft of the system block diagram. It will help me see the bigger picture when working on the system components. These are just a brain-dump and aren't set in stone.

eBay update

My 3.5mm gold connectors and servo/ESC tester have arrived. Will give the tester a go tomorrow, try to get an EDF going.