Flipdot Sign API

A simple http endpoint for pushing json serialized numpy arrays directly to the Hanover flipdot display.

Uses pyflidot to interface with the sign. It is small, simple and the best python3 flipdot class.

API

Endpoint: /api/dots

Post a json serialized numpy array directly to the endoint.

Example Curl request

curl -X POST -H "Content-Type: application/json" -d @nparray_test.json http://localhost:8080/api/dots

That is it. That is the api.

Getting Started

I am assuming you are on linux. It sohuld work under osx, but I cannot promise anything.

Checkout sourcecode

Check out this repo:

git clone https://github.com/company-lol/flipdot-server.git
flipdot-server.git

Edit the config file

cp config.ini.example config.ini
vi config.ini

You will want to make sure that the config file has all the right items in it and that they match your install:

; config.ini
[SERVER]
HOST = 0.0.0.0
PORT = 8080

[FLIPDOTSIGN]
COLUMNS = 96
ROWS = 16
ADDRESS = 1
USB = "/dev/ttyUSB0"
SIMULATOR = True

Run server

Build the app, cp the config example to config.ini, and run the server:

pip3 install -r requirements.txt
python3 app.py

Should output something like:

DEBUG:asyncio:Using selector: KqueueSelector
INFO:__main__:Instantiating server
INFO:__main__:Creating web app
INFO:__main__:Starting background tasks

Use Docker

Docker should be pretty straight forward.

docker-compose build
docker-compose up

If you want to have it connect to your USB serial adapter you will need to edit the docker-compose.yml file and un-comment out the following:

#devices:
#  - "/dev/ttyUSB0:/dev/ttyUSB0"

to

devices:
  - "/dev/ttyUSB0:/dev/ttyUSB0"

Using the API

If you are testing or getting started, you should go ahead and enable the simulator. This allows you to see what would be pushed through to the flipdot display without actually having the display hooked up. A nice way to debug. You can ensure that the simlulator is enabled by making sure the SIMULATOR = True in the config.ini.

Once you have everything configured and it works - you can change the config.ini to SIMULATOR = False and edit the docker-compose.yml to enable the USB device to be passed through.

Creating numpy arrays

You can create a numpy array represents all of the pixels of the flipdot display. It must be the same size as your flipdot display. For instance, if the flipdot display is 96x16, then the numpy array should be 96x16 as well.

Example code

import numpy
import requests
import json

sign_columns = 96
sign_rows = 16

image_array = numpy.full((sign_rows, sign_columns), False)
image_array[0][0] = True
image_array[sign_rows-1][sign_columns-1] = True

url = "http://localhost:8080/api/dots"

headers = {'Content-type': 'application/json'}
r = requests.post(url, data=json.dumps(image_array.tolist()), headers=headers)

This will push a numpy array to your api endpoint that has a pixel in the top left and a pixel in the bottom right.

Utilities

I will create some utility scripts that can use this API. I am thinking about making:

• Clock - A simple clock that is cron based that pings the API on the minute to display a clock
• MQTT Text renderer - a simple mqtt listener that posts a payload to the sign
• Image renderer - a way to render images

Help out

I would love a solid code review of the server app.py and some help making sure my async code works. ;)