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project dilemma. which colorful thingy to persue 1st?!

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wylie

Fri Jun 04 2010, 07:00AM

Registered Member #882 Joined: Sat Jul 07 2007, 04:32AM
Location:
Posts: 103

I got the STM32 ARM stamp-module that Bjorn suggested to me a month ago. It's great; It's like having a PC who's sole purpose is interfacing with hobby projects, and doesn't require hundreds of watts to run.

ST's firmware library seems really good, once you combine the reference manual with the example code they supply (it's a bit tough to understand unless you combine the two.) Though, I've only used 2 of the peripheral libraries so far, and that opinion might change once i start using the inputs and ADC/DAC. And of course, i spent at least 4 days trying to get my interrupts to work the 1st time..... I was using one of ST project examples to start from, and completely forgot about the OTHER .c file (aside from main.c) that was included in the build which contained the interrupt routines. Sure enough, once i stuffed my junk into that file, it worked.

Getting to the point of the thread...I've got two projects that i want to do RIGHT NOW, but can't decide which. I don't have the board space to do both.

1. an acrylic sign-holder, with an engraving, illuminated by r/g/b LEDs (r/g/b being separate "bulbs", as opposed to real RGB LEDs.) Basically, a desk ornament. I've got the program doing a test pattern of RYGCBM-andbackagain, plus it stops on white. I want to work out a smooth-fade-around-the-spectrum routine as well, and then add a button or two for an interface to select modes. BUT, I have no idea how I'm going to make it a stand-alone unit (ie: with its own uC, as opposed to running off the stamp.) and I also have no idea what i even want to engrave on the plastic. So, to keep working on this one, i just need to buy/salvage some buttons, figure out a way to get a 64pin lqfp onto the ornament, and then program the full-spectrum-routine plus some button interface, and BAM, i've got a sexy desk ornament. Oh, and deciding on an image for the engraving wouldn't hurt either

2. A matrix display. I've already wired up all the indicator LEDs I had in my box into a 4x8 matrix. One row green, two yellow, and one red. So what better to do with that than some sort of sound-level display for audio? Has most of the same barriers-to-completion as the acrylic display; like how to work that mega-pin SMD chip into the construction for the final build, and some button action. Also need to figure out the ADC.

I wired up the whole matrix before i realized i didn't have enough breadboard space to hook it up to the stamp, unless i pull up the r/g/b setup for the acrylic display. Yeah, i could put that stuff back some day....but should i just finish my program for the r/g/b thing before moving onto another project? I mean, if i get the program done, then i don't really need that project on the breadboard anymore. Until I work on the final build at least...gotta buy a toaster oven and rework it for reflow work, that's how i can easily incorporate those hentai-esque 64pin ARM chips

So, i can't really completely-finish either till i Get Ma' Reflow On. I think I'll learn more from #2, which could even make #1 easier to work on later.

Opinions?

Conundrum

Fri Jun 04 2010, 08:57PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

get another protoboard? :)

btw i came up with some code to do that, based on a tapped shift register preloaded with a PWM fade waveform.
each output feeds one of the LEDs resulting in a smooth fade-around.

wylie

Sat Jun 05 2010, 04:41AM

Registered Member #882 Joined: Sat Jul 07 2007, 04:32AM
Location:
Posts: 103

Damn, Conundrum! "Option 3" hadn't even occurred to me. Off to the shop...er, site. I was going to order a buttload of LEDs this week anyway

My color shifting code is already based on the pwm method. The program uses a triplet of PWM values (0 - 999) to control each color channel. I've used it to tune the relative brightness, since it's easier than swapping-out-resistors-till-the-day-i-die. I can't calculate it due to buying some unspecififed LEDs for that project. They were reasonably priced, and the color and brightness are good....but i got no way of finding a datasheet. Without that, it's all trial-n-error to get the max brightness without burning out the LEDs. I just haven't taken the time to work out how the program fades from one set of values to the next, but I'm sure i can figure it out. If i can't, there's always google

Anyway, back to the rgb project till my additional boarding arrives. Thanks for helping me think this through....i can't get any of my friends or family to stay non-comatose long enough to discuss my projects with them. OH, they like the results, but talking about it for more than 2mins just isn't possible. Add to that the fact that it takes me half-to-a-whole hour to explain what I'm trying to do....yeah, just better to ask the board.

Bjørn

Sat Jun 05 2010, 04:49AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

Go for the project with the ADC so you can do some proper data processing.

I have figured out the ADC, DAC and most importantly the DMA controller if you need any help with that. At the moment I am not using the firmware library. The early versions had some problems that made it pretty frustrating to use.

So instead I made some useful functions like configuring the I/O pins with a simple command like configPortA("---- ---- oooo oooo"); instead of a whole page of code (set PA0-PA7 to output, no change on PA8-PA15).

Hazmatt_(The Underdog)

Sat Jun 05 2010, 03:53PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

If you're going to be making signs and have the led's matrixed anyway, use the ADC and make a 10 band low frequency spectrum analyzer with a FFT.

Test equipment is always useful to have around even if you don't need it right away.

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