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Disassembling the Devo 7

A project log for Crazy Flie 2.0 Remote Control

A standalone remote control for the Crazy Flie 2.0

roman-gassmannRoman Gassmann 10/08/2017 at 15:370 Comments

After I received the Devo 7, I had to figure out how I can reuse its parts. Beginning with the most important (and also easiest) ones, the joysticks. Basically just some potentiometers which can be connected to the ADC of the uC (don't forget the RC-net for a basic filtering). Next part that had to be investigated was the display. After some logic analysing and research, I found out that the display features a HT1622 controller. With that known, I quickly was able to initialize the display. So the only thing left to do was to find the correct assignment of the segments. Even though, this was an easy task it took me a while (I also had to define the "Font" to write with the given segments). But hey, who said it's a work for 5 minutes, right? So after I was able to reuse the display... how about those buttons? Again some hacking revealed their connection to the uC (as expected in matrix form). Well that should be an easy part to reuse: just copying the matrix - connection. So keep on going to the next thing, the switches. Well the original board uses a HC589 to get the states of all switches. As this HC-Component is well known, why not stick with it? So again an easy and also feasible solution. This left me with just two parts left to analyse in the Devo 7. First, the beeper which is just a beeper ;-) that needs a PWM (Hi level 3V3 or 5V both are working (of course the volume at 5V is higher than at 3V3). Since it is not recommended (due to its current consumption) to drive such a component form the uC directly, a straight forward transistor network is needed here - easy again :-). So there is just one part left, the battery, that ugly pack of 8 AA-Cells. Its for sure that we wont use that in our new design. Instead I wanted to reuse a LIPO-cell from a broken phone ( one less that's laying around ;-) ). Furthermore, I should be able to charge this cell by a 5V supply through the charge-connector at the back of the Devo 7 - so some development needs to be done here but again not a big thing.

Now the next step will be the design of the schematics and also the layout of the new remote-control main-board. And yea... already looking forward to fly my Crazyflie with a very nice remote-control :-).

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