2015-10-27 21:36:28 +01:00
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# ser2neo
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## Overview
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ser2neo makes it easier to drive a NeoPixel ring by
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implementing the NeoPixel protocol in an ATTINY85 and
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exposing it through a serial interface.
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2015-12-31 10:36:05 +01:00
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Note: This is not an official Google product.
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2015-10-27 21:36:28 +01:00
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## Hardware
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This software was developed for a
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[OLIMEXINO-85](https://www.olimex.com/Products/Duino/AVR/OLIMEXINO-85-ASM/)
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ATTINY85 USB board with a
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[Adafruit NeoPixel 16 ring](https://www.adafruit.com/products/1463).
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It should work with any other
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[Digispark](http://digistump.com/products/1) clone. The
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implementation is very speed and timing sensitive. If it doesn't
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work check that PCIntDelay is correct for your CPU, clock speed, and
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bootloader.
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Pins:
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* PB0 is TXD
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* PB1 is DOUT and connects to the NeoPixel DIN
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* PB2 is RXD
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Connect the pins to a 3.3V serial interface such as the
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[FTDI serial cable](https://www.sparkfun.com/products/9717).
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See `client/` for a simple client library and demo applications.
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## Implementation
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NeoPixels use a single wire, 800 kHz, non-return-to-zero
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protocol. This implementation uses Timer0 in PWM mode where each PWM
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cycle is one bit. The PWM duty is updated each cycle.
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The serial interface is a half duplex, command/response based
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protocol that's designed to be mildly computer friendly. Data is
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transferred at 57600,N,8,1. Character
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stuffing is used to escape the special values, which are '\r' for end
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of frame and '+' for escape.
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The commands are:
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* `!` - sync. Responds with `OK sync`.
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* `?` - query. Responds with `OK` followed by the system ID, version,
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type, LED count, and colour order.
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* `l` - set LEDs. Followed by the LED data with three bytes per RGB
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LED. Responds with `OK`.
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-- Michael Hope <michaelh@juju.net.nz> <mlhx@google.com>
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