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MicroPython P9813

A MicroPython library for P9813 RGB LED drivers.

For example, the Seeed Studio Grove - Chainable RGB LED.

Installation

Using mip via mpremote:

$ mpremote mip install github:mcauser/micropython-p9813
$ mpremote mip install github:mcauser/micropython-p9813/examples

Using mip directly on a WiFi capable board:

>>> import mip
>>> mip.install("github:mcauser/micropython-p9813")
>>> mip.install("github:mcauser/micropython-p9813/examples")

Manual installation:

Copy src/p9813.py to the root directory of your device.

SPI Version

You can use either HSPI or SPI. This version is significantly faster than the bit-bang version. MISO is not used. The LED driver is write only.

SPI Example

Basic usage

import p9813

num_leds = 10
auto_write = False

# Using Hardware SPI
from machine import SPI, Pin

spi = SPI(1, 10000000, sck=Pin(18), mosi=Pin(23), miso=Pin(19))  # TinyPICO
chain = p9813.P9813_SPI(spi, num_leds, auto_write)

# Or using Software SPI
# from machine import SoftSPI, Pin
# spi = SoftSPI(baudrate=100000, polarity=1, phase=0, sck=Pin(4), mosi=Pin(5), miso=Pin(6))  # TinyS2
# chain = p9813.P9813_SPI(spi, num_leds, auto_write)

# Set the first LED to red. (red, green, blue)
# In a chain, the first LED is closest to the MCU
chain[0] = (255, 0, 0)

# Set the second LED to green
chain[1] = (0, 255, 0)

# Set third LED to blue and forth LED magenta
chain[2:4] = [(0, 0, 255), (255, 0, 255)]

# Write data to all LEDs
chain.write()

# What colour is the forth LED?
print(chain[3])
# (255, 0, 255)

# How many LEDs in the chain again?
print(len(chain))
# 10

# What are the first two colours?
print(chain[0:2])
# [(255, 0, 0), (0, 255, 0)]

# What are all the colours?
print(chain)
# [(255, 0, 0), (0, 255, 0), (0, 0, 255), (255, 0, 255), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0)]

# Turn on auto-write, so you don't have to call write() after each change
chain.auto_write = True

# Make all LEDs red
chain.fill((255,0,0))

# Make all LEDs green
chain[0:10] = [
    (0, 255, 0),
    (0, 255, 0),
    (0, 255, 0),
    (0, 255, 0),
    (0, 255, 0),
    (0, 255, 0),
    (0, 255, 0),
    (0, 255, 0),
    (0, 255, 0),
    (0, 255, 0),
]

# Draw a rainbow by modifying the buffer directly
# Each 4 bytes = 1 LED (checksum, blue, green, red)
chain._buf = bytearray(b"\xc3\x00\x00\xff\xc6\x00K\xb4\xc9\x00\x99f\xcc\x00\xe4\x1b\xcc3\xcc\x00\xe4\x81~\x00\xf0\xcc3\x00\xf0\xe4\x00\x1b\xe1\x99\x00f\xd2K\x00\xb4")
chain.write()

# Turn off all LEDs
chain.reset()

Bit Bang Version

This version works exactly like as the SPI version, only the serial data is written by sending pulses on two output pins (clock and data).

Bit Bang Example

Basic Usage

import p9813

num_leds = 10
auto_write = False

from machine import Pin

pin_clk = Pin(4, Pin.OUT)
pin_data = Pin(5, Pin.OUT)
chain = p9813.P9813_BITBANG(pin_clk, pin_data, num_leds, auto_write)

# Make all LEDs red
chain.fill((255, 0, 0))

# Set the second LED to green
chain[1] = (0, 255, 0)

# Set the last 8 LEDs to blue
chain[2:] = [(0, 0, 255)] * 8

# Turn off all LEDs
chain.reset()

For more detailed examples, see examples.

If you mip installed them above, you can run them like so:

import p9813.examples.basic

Chaining

You can connect multiple LEDs together to form a chain. For each additional LED, an additional 4 bytes need to be sent per refresh. The more LEDs you add, the longer it takes to write.

Parts

• Grove - Chainable RGB LED
• Grove 4P Universal Buckled Cable
• Grove 4P Male Dupont Conversion Cable
• TinyPICO
• TinyS2
• WeMos D1 Mini

Connections

If you are using the bit-banged version, you can use any output GPIO pins for clock + data.

If you are using the SPI version, you need to use the SPI pins available to your MCU.

If you are chaining multiple LEDs, clock out -> clock in, data out -> data in, eg.

Links

• micropython.org
• P9813 datasheet
• TinyPICO Getting Started
• WeMos D1 Mini

License

Licensed under the MIT License.

Copyright (c) 2017 Mike Causer