I have had great progress since my last update. The PCB for the remote controller has been sent out to OSHPark and I have actually received the boards already. They are all soldered up and everything. I actually received the boards almost a month ago, so I have been meaning to make this post for over a month now.
Anyways, the board is all populated and I must say, it most certainly was a pain soldering all the SMD stuff on it. The MSP430 on the board is a TSSOP so that wasn't too bad, but the buck-boost converter came in a QFN package (Thanks TI....). In case you are not familiar with QFN, it doesn't have pins that stick out, it just has pads on the side and the bottom that gets soldered to pads on the PCB. There was even a pad on the bottom in the middle, so it was clear that I had to reflow that QFN rather than doing good ol' soldering with my Radioshack soldering iron.
Also, I must point out here that Newark (my supplier for electronic parts, awesome company) messed up my order for the first time! I have ordered boxes of stuff from them, and they had never messed up anything but this time, they sent me a 75K resistor instead of the 1.5uH inductor I ordered! The inductor is the current storing inductor for the buck converter so it is an important component. I soldered on the 75K resistor they labeled as the inductor, and of course the power supply did not work. For the life of me, I could not figure out what was wrong with the circuit. After many sleepless nights, I finally measured resistance across the so-called inductor and saw 75K resistance. Inductors might typically have a couple of Ohms of resistance across, but 75K is waaaayyy tooooo high! So I knew the inductor was not actually an inductor. I had an 0805 1.5uh inductor lying around the house, so I jerry rigged it to fit on an 0603 pad.
Anyways, here are some pictures from a month ago. Now everything is soldered, but in the picture on the bottom, I only had the bare minimum soldered.
Anyways, the board is all populated and I must say, it most certainly was a pain soldering all the SMD stuff on it. The MSP430 on the board is a TSSOP so that wasn't too bad, but the buck-boost converter came in a QFN package (Thanks TI....). In case you are not familiar with QFN, it doesn't have pins that stick out, it just has pads on the side and the bottom that gets soldered to pads on the PCB. There was even a pad on the bottom in the middle, so it was clear that I had to reflow that QFN rather than doing good ol' soldering with my Radioshack soldering iron.
Also, I must point out here that Newark (my supplier for electronic parts, awesome company) messed up my order for the first time! I have ordered boxes of stuff from them, and they had never messed up anything but this time, they sent me a 75K resistor instead of the 1.5uH inductor I ordered! The inductor is the current storing inductor for the buck converter so it is an important component. I soldered on the 75K resistor they labeled as the inductor, and of course the power supply did not work. For the life of me, I could not figure out what was wrong with the circuit. After many sleepless nights, I finally measured resistance across the so-called inductor and saw 75K resistance. Inductors might typically have a couple of Ohms of resistance across, but 75K is waaaayyy tooooo high! So I knew the inductor was not actually an inductor. I had an 0805 1.5uh inductor lying around the house, so I jerry rigged it to fit on an 0603 pad.
Anyways, here are some pictures from a month ago. Now everything is soldered, but in the picture on the bottom, I only had the bare minimum soldered.
Here are pictures of the board:
There are other SMDs on there that are just impossible to solder with my awful soldering iron, so Jeff to the rescue. He recently built up an awesome electronics lab in his house and has kindly let me use his equipment. He has a microscope for tiny SMD soldering (Awesome!), an awesome Weller fine-tip crazy-fast heating up $300 soldering station, an oscilloscope and of course a signal generator. There are also two tiny transistors that come in 6-pin tiny package that I use on the board, and I actually messed up soldering them big time.
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| Jeff's Lab |
Finally, I am sharing two videos, one of the controller with LEDs flashing, and the other with the RC Car driving around.
Thanks guys!
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