suggestion for a smaller and cheap

SpokePOV kit for bikes

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casainho
 
Posts: 29
Joined: Mon May 12, 2008 7:09 pm

suggestion for a smaller and cheap

Post by casainho »

Hello :-)

Why not use an AVR MCU with more output pins, with 4KB internal EEPROM an drive directly the LEDs? and less LEDs?

I also would use SMD components as SOIC MCU.

A LED bar can be constructed without a PCB, just wires and some sort of plastic to suport and with less ICs it makes a smaller, lighter product.

I was expecting to see the program to make the graphics for Linux......

Thank you.

The_Don125
 
Posts: 373
Joined: Tue Mar 06, 2007 11:51 pm

Post by The_Don125 »

Well, a bigger MCU really will only marginally help costs.

The tiny2313 used along with the 8 shift registers and EEPROM cost about 2.15 + 0.48 * 8 + 0.50 = 6.49.

The smallest MCU that has > 30 output pins and > 4k memory space is the ATMEGA164, which costs $4.82, so a savings of $1.67 USD.

But, now you are wiring each LED directly. Rather than sending out 8 data lines to the shift registers, now you are sending 30, which means the PCB must be wider, which increases the cost.

If you wire it point to point, its not much better, because now you'll have a bundle of 31 wires coming out of the controller board. Its also not very kit-friendly.

The SOIC idea is not very kit-friendly, but if you can do it, more power to ya.

A Linux SpokePOV graphic design program would be nice though...
Last edited by The_Don125 on Mon May 12, 2008 7:40 pm, edited 1 time in total.

adafruit
 
Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm

Post by adafruit »

1. because people like lots of LEDs
2. 595's are very cheap, cheaper than a bigger micro
3. SOIC microcontrollers are not cheaper or significantly smaller
4. plastic will shatter easily

casainho
 
Posts: 29
Joined: Mon May 12, 2008 7:09 pm

Post by casainho »

ladyada wrote:1. because people like lots of LEDs
2. 595's are very cheap, cheaper than a bigger micro
3. SOIC microcontrollers are not cheaper or significantly smaller
4. plastic will shatter easily
Thank you. I will have more time reading the project... sorry for the quick questions.

I work in a company that develop and produce products with LEDs, we sell a lot stop and tails lamps for cars, for all Europe - we are a small company, however. I am novice, I do programing of AVR 8 bits, the MCUs that we use. http://www.plurirede.pt/

Congratulations for use Atmel!! Atmel stimulates GCC-AVR, Free Software tools for development and they have a lot of good application notes - very good for community development, hacks - I use for my work the GCC-AVR, AVR-Libc and USBProg.

I use GNU/Linux Ubuntu so I will not be able to program the graphics?

I like a lot bikes and I am involved in Critical Mass in Portugal :-) - http://www.massacriticapt.net

I hope to learn with this project, buy and use :-)

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