What is it?

The STMicroelectronics STM32L4R9I-EVAL Orca Plus Evaluation Board (Mouser ref. 511-STM32L4R9I-EVAL), the (much) bigger brother of the STM32L4R9I Discovery kit (Mouser ref. 511-STM32L4R9I-DISCO) is intended as a demonstration and development platform for the manufacturer’s Arm-Cortex-M4-based STM32L4R9AI microcontroller. With its dimensions of 173 x 156 mm (6.8 x 6.2”) it is a pretty large board, especially compared to the Arduino-sized development boards that are so popular today.

stm32l4r9i-eval kit
The STM32L4R9I-EVAL kit comes with two displays (only one shown here), iPhone earbuds, an 8 GB microSD card and a stylish USB stick, plus a nice collection of various USB cables.

Despite the size of the board and the many components that populate it, it is the unusual 30 mm (1.2”) circular smartwatch display just below the centre that attracts the user’s attention and curiosity. This display is more or less the star of the board, while the MCU itself is so unobtrusive that it's easily overlooked.

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First impression of the STM32L4R9I-EVAL

When unboxed and powered for the first time (use micro USB connector CN21 ‘ST-Link/V2-1’ in the lower-left corner to connect the board to a Windows PC) the STM32L4R9I-EVAL board (I like Orca Plus better but that seems more like an internal project name) it will show up as a 2-MB removable drive, a serial port and an ST-Link debug device. To make this happen you may have to install the ST-Link driver first. If you do, you can download it from the ST-LINK/V2 page at the ST website.

The microSD card has music on it

Insert the microSD card in its socket and touch the circular display (BTW, do not remove its protective film, as the display will get dirty really quick otherwise). You now have access to three demo programs STemWin, TouchGFX and Embedded Wizard. These names refer to the providers of the graphical libraries used to build these demos (emWin by Segger).

stm32l4r9i-eval kit as smartwatch
Look, my cool new smartwatch!

Take your time to explore the demos

My personal favourite is TouchGFX as I like its graphics best, but STemWin is free. Besides showing off the capabilities of these libraries and measuring MCU power consumption these demos do not have much to offer (listen to music on the microSD card, play a game, record sound, system info).