Archive for November 2009
It’s finished! (almost). The Motor Board PCB arrives and I’ve soldered all components together. The final results looks awesome to me! Most beautiful that I’ve planed. There’s some parts that I don’t solder, because I need purchase a SMD rework station (all solders on this robot are made with a ordinary solder station).
I found two problems with this design:
- I’ve used the RA4 pin of PIC18LF452 for digital I/O, but unfortunately according to datasheet, that pin is a open drain. To operate like a common digital I/O it’s need a pullup resistor, but I don’t put it on my design. I need to solder the pullup 10kΩ SMD resistor. Lesson: All the times, read the entire datasheet before use any device pin.
- In my Eagle motor library, I don’t provide horizontal restrictions to the motors area. Then, a little decouple capacitor stay above the motor, touch the white bracket motor house. This make a bad contact between boards. This capacitor it’s for crystal stabilization, so I removed it.
Well, even with all the issues:
- Inverted connectors on boards;
- Capacitors with wrong package (remember: 3406 don’t is 0603!);
- Open drain pin without pullup;
- Parts that I can’t found where purchase them;
… I think the whole project was a success. The robot works well, silent, smoothly. They are solid, very small and useful. The final result is a perceived evolution of the prototype, you see next:
That’s the video of your first tests:
Now, the wireless part (NRF24L01+ transducer) waits to be soldered. It’ll on the party next month. So, the whole project has been closed and I’ll work on the software development, that I only write a very basic functions for test and maze solves.