Controlling 32 LED Strip with HiTechnic Protoboard

[kfilar]

I would like to purchase your "Digital RGB LED Weatherproof Strip 32 LED". However, I am not certain we can control it. Your warning about the tricky timing issues of the 30 LED strip led us to the 32 LED strip.

If we were controlling it with an Arduino I wouldn't hesitate, because we would simply download your drivers, and assume we could figure out how to use those from your examples.

However, reading through your comments in the LPD8806.cpp file on GitHub, makes me wonder if we have the technical capabilities to understand how to control it with a HiTechnic Super Prototyping Board. We also only have access to a standard 9V battery for LED power.

As far as the battery, we would add a simple 5V voltage regulator and limit ourselves to about 18 LED's or so and only turn them on one or two at a time. Presumably we could switch between them every 100ms or so.

With the HiTechnic prototyping board, we have lots of experience writing out to digital pins very similar to an Arduino at 0 or 3.3V. Our kids can then have fun writing code to do what they want. However, are we going to be able to write a function like: turnOnLed(ledNumber, ledBrightness, ledColor)...? I saw a lot of object oriented code that was designed for the Arduino or other boards, but it looked fairly complex, presumably because of the weird addressing scheme of the on-strip LED controllers (passing on unused data from LED to LED, or something like that to address particular LEDs).

I searched for HiTechnic in the LED portion of the forum and it didn't return a hit. We're pretty resourceful and determined, but would like to know if we're headed for inevitable failure.

Thanks very much,
Ken

[adafruit_support_bill]

Is this an FTC related project? My understanding of this year's rules allows additional microcontrollers provided that they were powered from the protoboard.

Current output from the HiTechnic protoboard itself is very limited, but I think there is enough to run a Trinket. http://www.adafruit.com/products/1501
This has enough horsepower to control a strip & the libraries are available for both LPD8806 strips and our WS2812 NeoPixels: http://www.adafruit.com/index.php?main_ ... =neopixels

You could then write a simpler protocol from your NXT to send commands to the Trinket.

[kfilar]

Yes, this is FTC related.

I believe you are correct on the additional microcontroller power.

Yes, the current supplied from the HT Super Prototyping board is indeed very limited:
3.3V at 15mA
5V at 8mA
9V at 8mA (this is unregulated and therefore is more like 7.4V to 8.4V depending on how recently the NXT battery was charged.)

I didn't see a spec sheet on the Trinket, so I'm not sure what sort of logic current it requires. Would it be better to get the 5V Trinket receiving 8mA or 3V Trinket receiving 15mA? We'll only be putting out 3V from the I/O pins to the LED strip, I presume, so maybe the 3V Trinket would work and the 15mA current from the ProtoBoard would be better? I presume we can connect the power and ground on the LED strip directly to the 9V battery. Our kids are using a quadruple half-H-Bridge IC to control standard LED's now, and that is FTC-legal per the game forum.

I see that the Trinket doesn't have a serial port, so I'm not sure how we would troubleshoot the programming that converts incoming signals from the HT SuperPrototyping Board to the library functions we would load from your libraries. Maybe they're just such simple programs that it's not an issue.

Are you an FTC coach, FTA, organizer or something else? I am an FTC coach. The kids should get to play with this after our first tournament in a week, especially if their robot performs like they're hoping and not needing to devote their time to higher priority tasks.

Thanks for your reply,
Ken

[adafruit_support_bill]

The Trinkets are based on the AVR ATTiny85. The 5v Trinket runs at 16MHz and needs about 10 mA. The 3.3v version runs at 8MHz and needs about half that. So definitely, the 3.3v is the one you want.

These are pretty bare-bones processors, but they are a great low-power/low-cost alternative for simple tasks such as this. Most programs are pretty simple so the lack of a serial port is usually not a major issue.

Yes, I'm a mentor for a couple of FTC teams. Our first tournaments are next week as well. Good luck to your team!

[kfilar]

Thanks very much,

I ordered the Trinket and LED Strip.

Good luck as well to your teams.

Ken