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  1. #11
    Senior Membrane spirilis's Avatar
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    Yeah I do toner-transfer but this atmega1284P arduino shield-compatible board I'm playing with was created by Iteadstudios I think (by one of the folks on arduino.cc)... Beautiful board, having rolled a number of single-sided toner transfer boards I drool over the detail.

    I'd heard about PIC years and years ago, they were practically a gold standard in MCUs for a lot of applications were they? My thoughts is that I should stick with AVR since I know it well enough now, and dabble in ARM Cortex when I need to move up... Although I did just get my hands on that $4.30 TI LaunchPad thingamajig. Too many toys, not enough time!

    Another near-future project I intend to complete is a MIDI postprocessor for some Yamaha toy digital drumset I bought years ago... it has a firmware bug where the hi-hat pad only sends an open-hihat MIDI instrument regardless of whether the pedal is depressed or not. Was going to pass the pedal signal through an AVR and passthru back to the drumset, then clean that bug out of the MIDI stream, and also add the ability to inject play-along MIDI programs triggered/initiated by a drum hit or whatever... haven't thought the last part out too much, but I am receiving a couple ATmega32U4 processors and I'm going to build that project as not just a MIDI postprocessor but an actual MIDI-USB adapter (I've seen a project where someone did that with the ATmega8U2 shipping with newer Arduino Uno and Megas, so I'll try to adapt that code for my uses)
    intp | type 9w1 sp/sx/so

  2. #12
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    With toner transfer, I can easily do double sided surface mount boards. I've been using magazine paper, so I kept the trace/spacing at 15 mil because paper fiber tended to get stuck between the traces. They need to be removed by hand. I recently switched to HP presentation paper. I didn't etch yet, but a test transfer with 8 mil traces went perfectly. The paper lifted off by itself after less than 5 minutes of soaking, leaving a perfect, etch ready board. I etch with copper chloride, which can be regenerated indefinitely.

    I like the AVR better than the PICs but the latter has a DSP variant that can do math very quickly. I've been experimenting with stepper motor and servo motor controllers.

  3. #13
    Senior Membrane spirilis's Avatar
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    Someone (old EE guy) suggested Staples 32lb Glossy Color Laser paper, I've been giving it a try so far with success. A board with some 5.9mil spacing experienced failure (copper bridging) in 1 out of 24 instances so I know that's pushing it beyond the limit but I think 7mil+ should work perfectly.
    intp | type 9w1 sp/sx/so

  4. #14
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    What was causing the bridging? Was the toner smearing?

  5. #15
    Senior Membrane spirilis's Avatar
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    Good question, didn't really get a good inspection of it before the etch. I found it after the fact.
    Could have been toner smear as I suspect my printer is laying down the toner pretty heavy. I could try backing off the settings but TBH ..... I'd rather leave it alone, it works well enough
    intp | type 9w1 sp/sx/so

  6. #16
    Senior Membrane spirilis's Avatar
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    Well, my big project for my wife's car is finally installed (or in a state of being installed...) and I've had enough playtime to tinker and figure out things that have gone wrong.
    1. The digital compass (LSM303DLM 3-axis magnetometer+accelerometer used as a tilt-compensated compass) needs calibration, or rather, the user needs to develop the appropriate high & low readings for the magnetometer axes to get a reasonable amount of accuracy. It also feels like there's a slight bias in the reading, but I wonder if that has to do with Magnetic North vs. True North, which I am not compensating for yet. The surface where it's mounted I believe is flat and parallel to the frontward direction of the car, but that could be slightly off too.

    For now I've adapted the firmware (using Arduino 1.0 to an ATmega1284P target) to continually evaluate the response of the magnetometer and compare to its own known max/min values, if the new reading pushes that further it will update its max/min and commit the new values to EEPROM. It was fun taking it on a ~30 mile drive tonight and watching it learn and become more stable & accurate.

    2. A power-off switch on the PSU board in the trunk ... I am just going to desolder, as I have suspicions the switch is somewhat loose/flaky and accidentally trips when you slam the car door sometimes, turning everything off. There's a wire brought out which turns off the PSU when it's attached to GND (exact same thing as that switch onboard the PCB does...) and the 12V power feed inputs use barrel-type quick disconnect fittings so it's easy to disconnect anyhow.

    Otherwise, I need to get my under-hood external temperature sensor done (found a pre-drilled hole in the firewall which I may be able to use to route the cable between the interior & under-hood, which helps me a LOT) and then it's a fully-functioning "phase 1" implementation of the project. Currently it has a 16x2 LCD display showing time, compass heading, temperature from inside the trunk, and the date on the bottom line. I'll take pics soon.
    intp | type 9w1 sp/sx/so

  7. #17
    Senior Membrane spirilis's Avatar
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    Any of the uC nerds in here use Renesas microcontrollers before? I apparently "qualified" for one of those free RX62N development kits (link) and just got it today.... Slick board, lots of hardware, and the uC looks like some sort of ARM Cortex-M competitor of sorts. From further reading that appears to be exactly what it is--a Japanese show of force against the ARM hegemony I guess (lol). First time touching a 32-bit MCU though. I haven't installed the development software yet.

    http://am.renesas.com/products/mpumcu/rx/index.jsp
    intp | type 9w1 sp/sx/so

  8. #18
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    I used the 16 bit versions. The most notable feature was that it had 2 sets of working registers so that it was not necessary to save the data to the stack during an interrupt. The worse feature was the compiler user guide. It was nothing more than pages after pages of screen captures with obvious comments. "Click on FILE and the file menu will pop up."

    Low cost micro-controllers have gotten so powerful that I rarely select one based on the architecture. I usually go by peripherals and the quality of the free development tools.

  9. #19
    Senior Membrane spirilis's Avatar
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    Quote Originally Posted by Not_Me View Post
    I used the 16 bit versions. The most notable feature was that it had 2 sets of working registers so that it was not necessary to save the data to the stack during an interrupt. The worse feature was the compiler user guide. It was nothing more than pages after pages of screen captures with obvious comments. "Click on FILE and the file menu will pop up."

    Low cost micro-controllers have gotten so powerful that I rarely select one based on the architecture. I usually go by peripherals and the quality of the free development tools.
    Lol @ the compiler manual, that sounds bad. So far the tools look promising but that's because some company (KPIT Cummins?) ported GCC over to it, called GNURX, and it integrates both with Renesas' HEW IDE and KPIT's own version of Eclipse (although I couldn't get the KPIT GNURX tools to recognize the Eclipse install, oddly enough, but it does integrate with the HEW IDE). The RX chips sound neat, with plenty of connectivity but from what I gathered on their site's parts list, most of the small-pin count USB ones are still "in development" and not released. The ones with USB peripherals currently available for purchase are 100+ pins (a tad less friendly for DIY work, IMO). Anyway the board was free, so I figured I'd give it an honest look.
    --edit--
    Almost forgot, there was a free book written (basically a college textbook) that features the dev board & chip- http://am.renesas.com/media/products...CONTROLLER.pdf
    Looks like it's written for the newbie, literally for a college course on embedded systems development, but I'm going to skim through and see what I can get out of it.
    intp | type 9w1 sp/sx/so

  10. #20
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    Quote Originally Posted by spirilis View Post
    The RX chips sound neat, with plenty of connectivity but from what I gathered on their site's parts list, most of the small-pin count USB ones are still "in development" and not released. The ones with USB peripherals currently available for purchase are 100+ pins (a tad less friendly for DIY work, IMO). Anyway the board was free, so I figured I'd give it an honest look.
    The pin count tends to be excessive in the higher end processors. I been using the DSPIC for my DIY projects, primarily because they are available in user friendly packages.

    The RX looks like a very capable chip. I'd be interested in what you think of the development environment. The kit would be much more useful if it allows the onboard JTAG debugger to be used on other chips.

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