It Started With a Hardware Limitation I have been using Quectel GNSS modules in my designs for a while. They are reliable, well-documented, and the support ecosystem is solid. But the module I had been using had one problem that I kept running into: no external antenna support . For most projects that is a minor inconvenience. For a marine vessel monitoring and control system , it is a non-starter. A vessel hull blocks sky view, antenna placement is critical, and the difference between a clean fix and no fix at all often comes down to whether you can mount the antenna where it actually has line of sight. An integrated antenna in a sealed enclosure below deck simply does not cut it. So I went directly to Quectel. The Conversation With Quectel I reached out through their official sample request channel. I was not expecting much — most component manufacturers have a standard process: fill out a form, wait, get a few uni...
After the the part 1 of this episode i had some weird problems with the ATmega1284p. Sometimes i am able to upload the sketch via ISP and UART side also having some issues to upload sketches and use as an serial port. So i ask some assistance from the letmakerobots.com and explained whats going on with my 1284p.
Since i boot loaded it recently, i did not have any idea of what might be the cause. Finally bajdi from LMR replied me and after few conversations with him, he mentioned that he have used 1284p lots of time and this guy built robots, controlling lots of servo from it. So my boot-loading is perfect.
When i run single servo sweep sketch the jittering and wobbling starts and stops. So i planed to take the circuit out of bread board ( which have created problems and weird interference a lot for me) and build it on copper strip board which is in the image above.
With the proper smoothing capacitors and supply it worked. I manage to upload the sketches via UART side and controlling servo was perfect. no more unknown problems.
When the servo gets crazy
I advice people out there to use buck based voltage regulators not the crappy old 7805's. LM2596-5 is good one to make a 5v supply circuit and it monitors the output from feedback and simply saying it more like a DC to DC converter.
Special thanks to Bajdi (http://www.bajdi.com/)
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