LEDs were my fetish since I've managed to light first of them up, using 51 uc. This project is the result of this fascination.

Single SPIN unit is built of two boards:

• each of the two boards has 32 LEDs on each side
• both boards are equipped with single AA battery socket

SPIN can hold up to 16 images (32x256 radial pixels) which can be edited by user. It displays images only if bike is moving fast enough to let ti display persistent images (so it does not consume energy thoughtlessly).

Power source: 2x AA batteries
Using higher supply voltage would allow using different LEDs colours and minimize the risk of MCU going nuts (or detecting brownout condition), but considering weight of AA batteries I think it won't be the best idea.

MCU: ATmega32L
It works just below the border of official supply voltage.As device does not have to be totaly fail-safe I do not give a damn about it. Using brown-out detector would be reasonable, but It results in MCU staying in reset if the voltage drops to much- for example when the battery goes dead (and staying in reset is desired), or when to many LEDs are lit up (staying in reset then is a mess).

Look for attachments at the bottom of the post, to get SPIN schematics and PCB layout.

[img_assist|nid=25|title=Let your wheels cheer up! ;)|desc=|link=node|align=left|width=240|height=180][img_assist|nid=27|title=Hall sensor and magnet|desc=|link=node|align=right|width=240|height=180][img_assist|nid=28|title=Single SPIN module - two board with total of 64 LEDs each|desc=|link=node|align=center|width=240|height=320]