This section is under development
GitHub DEV branch: https://github.com/growboxguy/Gbox420/tree/Dev

Raspberry Pi Pico W

Goals:

Pico W vs Arduino Nano R3 main differences:

Raspberry Pi Pico W

2 Mb flash26 × multi-function GPIO pins: 3  x Analog pins,
2× UART, 2× SPI controllers, 2× I2C controllers, 16× PWM channels
Datasheet

Hold the BOOTSEL button while connecting the Raspberry Pi Pico to a PC and it will show up as a drive:

Development environment setup

UPDATE: The entire process of setting up the Pico C/C++ SDK  (Cmake, Visual Studio,Pico SDK, downloading and building the Pico examples) on Windows is now automated. Download the latest release from: https://github.com/raspberrypi/pico-setup-windows

elect both the Show ReadMe (super useful if you are new to Visual Studio), and the Clone and build  options.

Also install the latest Arm GNU Toolchain AArch32 bare-metal target (arm-none-eabi) and select it as an Active Kit in Visual Studio code.

Manual installation

To configure the development environment follow this Raspberry Pi Pico C/C++ Toolchain on Windows with VS Code guide. It will guide you through installing Visual Studio Code, Arm Toolchain, MinGW, Cmake, Python, Git, Pico SDK, and setting up the local environment variables.


Notes:

Pico Examples

Install the pico examples using Git Bash:

echo mingw32-make %* > /c/VSARM/mingw/mingw32/bin/make.bat

mkdir /c/VSARM/sdk

mkdir /c/VSARM/sdk/pico

cd /c/VSARM/sdk/pico

git clone -b master https://github.com/raspberrypi/pico-sdk.git

cd pico-sdk

git submodule update --init

cd ..

git clone -b master https://github.com/raspberrypi/pico-examples.git

Based on the  2.2. Building an SDK example chapter of the Pico W - Connecting to the internet guide prepare the build files for the Pico examples using Git Bash:

cd /c/VSARM/sdk/pico/pico-examples

mkdir build

cd build
cmake -DPICO_BOARD=pico_w -DWIFI_SSID="Your Network" -DWIFI_PASSWORD="Your Password" .. -G "MinGW Makefiles"

Blink example

In Visual Studio Code open the folder:  C:\VSARM\pico-examples\pico_w\wifi\blink

cd C:\VSARM\pico-examples\pico_w\wifi\blink

mingw32-make

The result should be several binary files generated inside the Blink folder. 

Copy the picow_blink.uf2 file to the Pico W. The board will automatically reboot and the LED should start blinking.

Wi-Fi scan example

Open the C:\VSARM\sdk\pico\pico-examples\pico_w\wifi\wifi_scan folder with Visual Studio Code. By default, the wifi_scan example prints the available networks to the UART output. To change this to the USB add the following lines to the CMakeList.txt:


pico_enable_stdio_usb(picow_wifi_scan_background 1)  # enable usb output

pico_enable_stdio_uart(picow_wifi_scan_background 1)  # enable uart output

Save the changes and re-create the make files using the Integrated Terminal (View/Terminal) - Git Bash. To set Git Bash as default press CTRL + Shift + P and type: Default profile

Update the make files using Git Bash:

cd /c/VSARM/sdk/pico/pico-examples/build
cmake -DPICO_BOARD=pico_w -DWIFI_SSID="Your Network" -DWIFI_PASSWORD="Your Password" .. -G "MinGW Makefiles"

Next, open the wifi_scan make files and create a binary:

cd /c/VSARM/sdk/pico/pico-examples/build/pico_w/wifi/wifi_scan

mingw32-make

Upload the picow_wifi_scan_background.uf2 file to the Pico W. After it reboots the Pico W will print the detected Wi-Fi networks to the USB output. To see this we need the COM number of the Pico W and Putty. Run the following command to check the COM port and bitrate:

mode

Open Putty and select Serial connection type:

The list of available networks are printed every 10 seconds:

MQTT server connection

To test relaying MQTT Subscribe and Publish messages between the Raspberry Pico W and an MQTT broker ( Mosquitto broker  running on Home Assistant OS in this case)  use the following test program written in C++:

MQTT client test

Update the Constants section with your WiFi and MQTT server parameters in the  MqttTest.cpp file:

// Constants - UPDATE THIS SECTION

#define WIFI_SSID "GboxNet"                      ///< WiFi SSID

#define WIFI_PASSWORD "SuperSecretPassword"      ///< WiFi Password

#define MQTTServerDNS NULL                       ///< MQTT server DNS name, leave NULL to use MQTTServerIP instead

#define MQTTServerIP "192.168.1.100"             ///< MQTT server IP

#define MQTTServerPort 1883                      ///< MQTT server Port

#define MQTTServerUser "MqttUser"                ///< MQTT server username, NULL if not needed

#define MQTTServerPassword "SuperSecretPassword" ///< MQTT server password, NULL if not needed

The test program utilizes the Light Weight IP open-source TCP/IP stack's MQTT client implementation (https://www.nongnu.org/lwip/2_0_x/group__mqtt.html). I made a middle layer called MQTTAPI  to make it easier to interact with the LWIP MQTT client. 

Expected test result: After a 10-second delay the Pico W should connect to the local WiFi, Find the IP address of the MQTT server, Connect to the MQTT server, and Subscribe to a test topic. Additionally every 30 seconds it should publish a randomly generated JSON to an MQTT topic. The test program currently supports MQTT 3.1.1 with password authentication. TLS cryptography is also supported by the LWIP library but is not implemented in the test.

You can use MQTT Explorer to view the Published messages, or the MQTT Last Will and Testament (LWT) message in case the Pico W goes offline. You can also send test messages to the Raspberry Pico W by publishing messages to the Subscribe topic set up in the test program.  By default, the following topics are used during the test:

Picoprobe

For debugging use a second Pico (Picoprobe) connected to the Gbox420 Pico's UART and SWD (Debug) port.
More info and setup guide: https://datasheets.raspberrypi.com/pico/getting-started-with-pico.pdf#picoprobe_section.  It will guide you through installing MSYS2, building OpenOCD, and uploading the Picoprobe UF2  binary.

While running debugging,  the USB output is not available on the Gbox420 Pico. Connect the Picoprobe's USB port to the machine you are using to develop, it should show up as an USB Serial Device on a COM port

Using Putty open the COM port using speed 115200

The Gbox420 Pico's UART output should be relayed to the Picoprobe's USB output

Building OpenOCD

Set up the prerequisites and build OpenOCD by running the following commands in MSYS2 - MINGW64:

pacman -Syu

pacman -Su

pacman --disable-download-timeout -S mingw-w64-x86_64-toolchain git make libtool pkg-config autoconf automake texinfo mingw-w64-x86_64-libusb

export PATH=$PATH:/mingw64/bin 

git clone https://github.com/raspberrypi/openocd.git --branch rp2040-v0.12.0 --depth=1

cd openocd

./bootstrap

./configure --disable-werror

make -j4 

Notes:  Run pacman - Syu multiple times, until it reports all packages up-to-date.

Start using the Picoprobe with OpenOCD by running:
 src/openocd -f interface/cmsis-dap.cfg -c "adapter speed 5000" -f target/rp2040.cfg -s tcl