The Meadow F7v2 from Wilderness Labs is an IoT platform for .NET based applications. It is an updated version of the Meadow F7 with double the flash storage and a better WiFi antenna. The Meadow F7v2 is still compatible with the Adafruit Feather form-factor, allowing the use of Feather Wings. The new version of the board has added castellations to the solder pads, so it can take headers or be surface-mounted to another PCB. Like other Feather boards, it has a connector for a LiPo battery, and has built-in LiPo charging capabilities.
The Meadow is built around an STM32F7 microcontroller with an ARM Cortex M7 core running at 216 MHz. Connected to the microcontroller are 32 MB of RAM and 64 MB of flash in external chips. The fourth large chip on the board is an ESP32 PICO providing Wi-Fi and Bluetooth connectivity. The board has both an integrated antenna and a connector for an external antenna with a software-controlled antenna switch selecting between the two.
The Meadow F7v2 has 25 I/O pins, six of them accepting analog input. It supports a wide range of serial peripherals, including I2C, SPI, UART, and CAN. (Software support for I2S isn’t available at time of writing but is promised soon.) All I/O runs at 3.3V. Be aware that the board runs a little hot.
We tested the Meadow F7v2 as part of the Hack Kit. The Hack Kit contains an impressive array of devices for prototyping including motors, displays, relays, sensors, switches, and LEDs. Even at $150, we would consider this one of the more generous starter kits for a microcontroller board. Before starting on any of the project walkthroughs, however, the first task is to get the on-board LED to blink.
Getting to blink requires a little work. Beginning with software downloads, you must install Microsoft’s .NET framework version 5 (not 6), then download the OS for the board and a DFU (device firmware update) utility to upload it to the board. Depending on your system, you may need to install a 3rd party utility to set the correct USB driver for the board. The documentation for all of this is a little rough around the edges, but there are instructions for Windows, Mac OS, and Linux. Error messages from the command line utilities were actually very helpful.
Once the OS, Meadow.OS, has been uploaded to the board, you need to set up the programming environment on the host computer. Wilderness Labs has created extensions for the Meadow in Microsoft’s Visual Studio. Here again, pay attention to versions. For Windows, you’ll need to have a Microsoft account (free) in order to find Visual Studio Community 2019 (version 16.11), unless of course you already have a Professional or Enterprise (not free) license. Mac users will need the equivalent 2019 version of Visual Studio. Linux users are on their own from this point forward.
When you create a new project in Visual Studio using the Meadow template, the default code will blink the LED in a sequence of colors. The walkthrough of this code does a good job of explaining how the code is structured and what the commands do. Another worthwhile stop in the documentation is the list of supported peripherals. This is where you should check to see if your favorite display, sensor, or Feather wing has a ready-to-use library. Each peripheral has a documentation page with example code and wiring instructions. The length of the list is pretty impressive. We found, however, that not everything is working with the new V2 board. It may take some time for the developers to find and fix all the bugs caused by new hardware.
Returning to the project walkthroughs, we found that they haven’t been updated for the V2 board yet. Some of them can be made to work with minimal tweaking, but others will require the developers to fix the aforementioned libraries. Given that the first version of the Meadow saw success, we can hope refinement of the V2 software support will come. In the meantime, you can visit Wilderness Labs public Slack channel for assistance. Both the developers and other users of the board are there and will try to help.
