provide a docker based build script

examples/raspi_pico/Dockerfile

@@ -0,0 +1,24 @@
+# A minimal dockerfile to provide a build environment to compile the JLed
+# raspberry pi pico JLed in a docker container. 
+FROM ubuntu:20.04
+
+LABEL MAINTAINER "Jan Delgado <jdelgado@gmx.net>"
+
+ARG TZ=Europe/Berlin
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN    echo ${TZ} > /etc/timezone && rm -f /etc/localtime \
+    && cat /etc/timezone\
+    && apt-get update \
+    && apt-get install -y git cmake gcc-arm-none-eabi libnewlib-arm-none-eabi \
+                          build-essential vim python3 python3-pip
+
+RUN mkdir /pico
+WORKDIR /pico
+
+# install SDK
+RUN    git clone --depth=1 -b master https://github.com/raspberrypi/pico-sdk.git \
+    && cd pico-sdk && git submodule update --init 
+
+ENV PICO_SDK_PATH=/pico/pico-sdk
+

examples/raspi_pico/README.md

@@ -1,19 +1,54 @@
 # JLed for the Raspberry Pi Pico
 
 This examples demonstrates how to use JLed on the Raspberry Pi Pico. The
-built-in LED and a LED on GPIO 16 will be faded.
+built-in LED (GPIO 25) and a LED on GPIO 16 will be faded.
+
+Also a Dockerfile is provided to enable a hassle-free build.
+
+<!-- vim-markdown-toc GFM -->
+
+* [Building the demo](#building-the-demo)
+    * [Docker build](#docker-build)
+    * [Local build](#local-build)
+* [Deploy the sketch to the Raspberry Pi Pico](#deploy-the-sketch-to-the-raspberry-pi-pico)
+* [Author](#author)
+
+<!-- vim-markdown-toc -->
+## Building the demo
+
+You have two options to build the demo. Either use a docker image (recommended),
+or setup everything yourself (consult Pico Quickstart Guide).
+
+### Docker build
+
+A [Dockerfile](Dockerfile) and a [build-script](build.sh) are provided to 
+enable a hassle-free build of the demo. The script will first build a 
+docker-image containing the build environment, then build the example.
+
+* run `./build.sh docker-image` to build the docker image with the build
+  environment (compilers, pico SDK etc.) - only needed to run once (as long
+  as the Dockerfile is not changed).
+* run `./build.sh compile` to compile the example. The resulting `pico_demo.uf2`
+  file to be uploaded will be found in this directory afterwards.
+* run `./build.sh clean` to clean up all files created during a build.
+
+### Local build 
 
 You need the [pico-sdk](https://github.com/raspberrypi/pico-sdk) and 
 necessary tools to compile everything installed.
 
 The `PICO_SDK_PATH` environment variable must point to the installation
 directory of the SDK.
 
-* to compile the demo sketch, run `cmake . && make` 
-* To deploy the demo sketch, press and hold `BOOTSEL` on the Pico and connect
-  the Pico to your PC. The Pico will now be mounted as an external drive. Copy
-  the file `pico_demo.uf2` to the mount point. The sketch should now start
-  automatically.
+To compile the demo sketch, run `cmake . && make`.  The resulting
+`pico_demo.uf2` file to be uploaded will be found in this directory afterwards.
+
+## Deploy the sketch to the Raspberry Pi Pico
+
+To deploy the demo sketch `pico_demo.uf2`, press and hold `BOOTSEL` on the Pico
+and connect the Pico to your PC. The Pico will now be mounted as an external
+drive. Copy the file `pico_demo.uf2` to the mount point. The sketch should now
+start automatically.
 
 ## Author 
 

examples/raspi_pico/build.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+# build the raspberry pi pico JLed example using a docker container.
+# Run "./build.sh docker-image" first to build the docker-image,
+# then run "./build.sh compile" to compile the example.
+#
+# Jan Delgado 02/2021
+set -eou pipefail
+
+usage() {
+    echo "$0: <docker-image|compile|shell|clean>"
+}
+
+build_image() {
+    docker build \
+        --build-arg="TZ=$(timedatectl show -p Timezone --value)" \
+        -t picosdk:latest .
+}
+
+run_cmd() {
+    docker run -ti --rm \
+        --user="$(id -u):$(id -g)" \
+        -v "$(pwd)/../..:/src:z" \
+        picosdk:latest "$@"
+}
+
+main() {
+    case $action in
+        docker-image) build_image ;;
+        compile)
+            run_cmd sh -c "cd /src/examples/raspi_pico && cmake . && make"
+            local -r line=$(printf '=%.0s' {1..75})
+            echo "$line"
+            echo "BUILD SUCCESSFUL."
+            echo "Now upload the file pico_demo.uf2 to your Pico manually."
+            echo "$line"
+            ;;
+        shell) run_cmd bash ;;
+        clean) git clean -d -x -f ;;
+        *) usage ;;
+    esac
+}
+
+action=${1:-""}
+main action
+

examples/raspi_pico/pico_demo.cpp

@@ -1,11 +1,14 @@
 // JLed demo for the Raspberry Pi Pico
+// Fade the built-in LED (GPIO 25) and a LED on GPIO 16.
+//
 // Copyright 2021 by Jan Delgado. All rights reserved.
 // https://github.com/jandelgado/jled
+//
 #include "pico/stdlib.h"    // NOLINT
 #include "jled.h"           // NOLINT
 
 int main() {
-    auto led1 = JLed(LED_PIN).FadeOff(2000).DelayAfter(1000).Forever();
+    auto led1 = JLed(25).FadeOff(2000).DelayAfter(1000).Forever();
     auto led2 = JLed(16).FadeOn(2000).DelayAfter(1000).Forever();
 
     while (true) {