STM32L4R9I-DISCO Discovery Kit - Review

Table of contents

RoadTest: STM32L4R9I-DISCO Discovery Kit

Author: dougw

Creation date:

Evaluation Type: Development Boards & Tools

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: CY8CKIT-062-BLE PSoC 6 BLE Pioneer Kit

What were the biggest problems encountered?: There is bound to be a significant learning curve with a product of this complexity and capability.

Detailed Review:

I applied for the STM32L4R9I-DISCO Discovery Kit road test for the following reasons:

  1. The kit is based on a powerful ARM Cortex M4 microcontroller integrated into a module with extensive interfaces and lots of memory
  2. The round OLED display with touch screen is very intriguing
  3. This microcontroller can do audio I/O as well as video I/o

It isn't everyday you come across a microcontroller card that can perform audio input and audio output - this kit has dual microphones and stereo audio output.

It isn't everyday you come across a microcontroller card that can perform video input and video output - this kit has interfaces for both, including a great OLED display.

The module has lots of other interfaces as well - including I2C, SPI, CANBUS, Grove, Mikro Click, uSD, and USB OTG.

Here is an unboxing video describing some of the features:

The round display instantly brings to mind wearable applications and low power consumption is an important feature of this microcontroller. Given its ability to handle audio and video, it is impressive that this MCU only draws a few mA of current. Even running at full throttle, it would run for 37 days on the charge in an iphone battery. If it was only running its real time clock, it would run for 300 years.

As mentioned, the round display is very intriguing. Many traditional optical systems use circular images – starting with actual eyes which have a conical field of view. Microscopes, magnifying glasses, binoculars and telescopes all have circular fields of view. It is not so much that round displays cut off the corners of an image, it is more like rectangular screens cut off sections of the naturally circular field of view. Round displays have some very unique aspects because of their shape. One aspect is that a rotating circle is not obviously rotating. I would like to explore this property.

The firmware applications that come loaded on the kit demonstrate the power of this microcontroller to handle smooth video on a graphics display and the versatility of of a capacitive touch screen user interface.


Lets take a closer look at the built-in audio firmware and what it can do.


Next up lets look at gaming and video playback capabilities.


One of the intriguing things I wanted to try with the circular display is using it for virtual reality applications:

I have ordered a camera from Newark so hopefully it will come in time to include in this road test. If not, I will still update the road test if and when I have further progress on this front. I also ordered a set of cardboard VR goggles that I can hack up to fit the module properly.



One final stretch goal is to experiment with an accelerometer to see if I can hold the display horizontal regardless of the angle of the module. I want to see if this makes it easier to read in a mobile scenario. A bit like having a stabilized display.


I have been downloading the software development tools to start learning how to program this kit, but there is a fairly extensive learning curve for me.


I will also measure power consumption of the whole module to complement the really awesome built-in current measurement system.


Conclusions so far

This is a very powerful microcontroller surrounded by lots of memory and extensive interfaces. Combining these features with low power make this kit suitable for a wide variety of applications, extending from simple apps like a wrist watch to complex apps like virtual reality.

The firmware that comes loaded on the device work immediately on power up and it does a good job of demonstrating a lot of impressive applications.

The included complete user interface of touch, microphones, audio output and video display open up the application space to include highly interactive systems.

I am very impressed that this microcontroller can manage these interfaces with such low current consumption - this level of capability really expands the horizons of microcontrollers.


Relevant links:

STM32L4R9I-DISCO Dicovery Kit Road Test Page

STM32L4R9I-DISCO Discovery Kit

STMicroelectronics STM32L4R9I-DISCO Dicovery Kit web page

STM32L4R Training

STM32L4R9I-DISCO Discovery Kit datasheet

STMicroelectronics software Cube development

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