Category Archives: micro-controllers

Open heart surgery

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OK, maybe not as dramatic, but it was just as vital.

With my final project deadline extended a week, I took a couple days of downtime to catch up on sleep. The all-nighters were adding up. Now I’m back and making some minor changes and a few fixes. Hopefully the thing will drive in reverse without catching on fire. If you don’t hear from me, send help.

Firmware for the not has been fleshed out and I’m looking forward to getting it coded. The loop is simple, checking the status of each input and setting a flag. That flag is passed to the three output functions, which run after the input stage. One exception is the turnaround() function, which is called by an interrupt on the whisker pin. Some output functions call themselves to complete a series of drive commands, for instance. This keeps things simple.

More to come.

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2015-04-23 · 20:05

All together now

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2015-04-20 · 21:18

Power blocking front end for analog IR proximity sensor array

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2015-04-01 · 16:54

Prepping additional IR sensors and control board

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As the 3 Sharp IR analog sensors in my robot design consume plenty of power, I’ve created an interconnect module that switches the load on and off by way of a TI nMOS FET. The microcontroller will periodically switch on the load, take a reading of the three sensors via ADC, and then switch the load off again. This process is controlled by  timer-based interrupt, storing the distance reading in a global variable.

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Filed under analog, edX, micro-controllers, Robots, Soldering

EE40LX: two sensor bridges with power blocking

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Two photo sensors with bridge and comparator front ends. Power supplied by a MCU pin, which switches high only when measurement is needed. This reduces overall power consumption, which is 11.355mW for both bridges.

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Filed under analog, edX, ICs, micro-controllers, Robots, Uncategorized

Help the CaTrakr find a home

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Present incarnation of the CaTrakr receiver, tests OK

Look at this poor homeless CaTrakr receiver. Its guts are hanging out, all vulnerable. The smallest tumble could be its last. What sort of home would you put it in, and why?

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Filed under DIY, ICs, micro-controllers, radio, regulators, Soldering, Teensy

At the dirty board house in Shenzhen

Through the marvels of globalization and modern technology, my solar charger design, dubbed the Solar Stage, has been sent off to a board house in China for low cost production. Thanks to DirtyPCBs, and its sassy yet functional website, I placed my order for 9 to 12 boards of my 10 * 10 cm 2-layer design for only $25 (including Hong Kong Post — no tracking). Yes, that’s no typo. $25. Oh, and a pick from 6 colours (I chose red). 5 * 5 cm is a jaw-dropping $14.

Front of the image generated by the DirtyPCBs website. After countless revisions, the board is ready. A Dangerous Prototypes Bus Pirate and a self-designed SD/flash combo board occupy the space unused by the Solar Stage.

According to the DirtyPCBs website, my Gerber files are transmitted through their automated system to a board house in the high tech heart of China, where it’s batched up with other boards and given the full treatment. The boards are then forwarded on to the DirtyPCBs agent, to be sent on to me. The whole process takes 6 to 8 days, not including the postage time (1 to 8 weeks for Hong Kong Post, dependent on your country). Amazing!

Back of my board order.

One feature I really appreciated is DirtyPCBs unlimited file revisions. Up until the point the board design is sent to the board house, the site accepts a re-upload of your design files. In the 31 hours before it was batched, I submitted five (5) updates. In my post-submission high, I noticed little bits I could improve and went over everything with a fine-tooth comb. Nothing like the thrill of working against the clock! Granted, it might be a bust, but at least I have some useful boards out of the experience.

To be honest, I enjoyed the cheeky language that peppers the website. Apparently the website was originally made as a joke poking fun at people complaining about the quality of a new process. Or a very clever dirty marketing. Either way, the results are impressive for the cost, so I decided to give them a shot. Tonight I received a notification saying my board has been batched up. Stay tuned for an update when my dirty boards arrive.

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Filed under Battery power, DIY, fabrication, ICs, micro-controllers, PCB design, Solar Stage, Teensy