Sponsored by Nordic Semiconductor.
Nordic Semiconductor has, once again, raised the bar in wireless technology by introducing the nRF54L series of System-on-Chips (SoCs). As an evolution of the popular nRF52 series, this new chip brings significant improvements in processing power, energy efficiency, and wireless capabilities.
In this post, I’ll be diving into my first impressions of the Flagship SoC within the nRF54L series, the nRF54L15. I’ll also provide a comparison to its very popular predecessor, the nRF52840 SoC.
Background and History
It’s been about a decade since Nordic Semiconductor released the nRF52 series of SoCs! This series, with the nRF52840 being the flagship SoC, became one of the most popular Bluetooth LE chipsets on the market, found in everything from smart appliances to beacons to wearables, medical devices, and a lot more.
Nordic Semiconductor has built its reputation not just on its cutting-edge SoCs but also on the developer tools and frameworks it provides. Over time, Nordic’s development environment went through a significant transformation—from nRF5 SDK and Segger Embedded Studio to the more modern Zephyr RTOS and Visual Studio Code (VS Code). This shift, while challenging, has proven to be an investment and a risk worth taking.
For many years, the nRF5 SDK served as the primary development platform for Nordic’s SoCs. This framework offered simplicity and reliability. Despite its strengths, the SDK’s limitations began to emerge. From its single-threaded nature to its tight coupling with the SoftDevice, it was less suitable for more complex or concurrent applications, particularly as IoT requirements grew.
As IoT and BLE applications evolved, Nordic shifted its focus toward the open-source Zephyr RTOS. This marked a significant pivot in its development strategy but sparked excitement and controversy.
As part of the transition, Nordic introduced the nRF Connect SDK (to replace the nRF5 SDK). Nordic’s evolution from the nRF5 SDK and SES to Zephyr and VS Code reflects a forward-looking strategy that prepares its ecosystem for the future of IoT. While the shift was not without challenges, it ultimately enabled more robust and scalable solutions for developers worldwide.
But how does this fit within the context of releasing the new nRF54L SoC series? We’ll find out in the “First Impressions and Hands-On” section!
Features Overview
The nR54L series is the first from Nordic to use the 22nm process node. It also includes a RISC-V processor for the first time. Let’s take a look at the most important features of the nRF54L15 SoC, while also comparing it with the nRF52 series Flagship SoC, the nRF52840 SoC.
Key Improvements Over the nRF52840
- Processing Power: The nRF54L15 doubles the clock speed from 64 MHz to 128 MHz, providing a significant boost in processing capabilities.
- Energy Efficiency: Despite the increased power, the new 22 nm process allows for improved energy efficiency, crucial for battery-powered IoT devices.
- Wireless Capabilities: Support for Bluetooth 6.0 and Channel Sounding puts the nRF54L15 at the forefront of Bluetooth technology.
- Memory: An increase to 1.5 MB of memory (compared to 1 MB in the nRF52840) allows for more complex applications and larger codebases.
- ADC Resolution: The upgrade from a 12-bit to a 14-bit ADC provides more precise analog-to-digital conversion, beneficial for sensitive sensor applications.
- Size: The nRF54L15 comes in an incredibly small 2.4×2.2 mm WLCSP package, significantly smaller than the nRF52840’s 3.544 x 3.607 mm package.
Other Notable New Features
The nRF54L15 introduces several new features that set it apart:
- Improved Radio Performance: With better receiver sensitivity and a new 4 Mbps proprietary mode, the nRF54L15 offers enhanced range and data throughput capabilities.
- Global RTC in System OFF mode: This feature allows for ultra-low power timekeeping, enabling new use cases for long-term battery-operated devices.
- Enhanced Security Features: The nRF54L15 includes advanced security features like TrustZone isolation, a new cryptographic engine with side-channel leakage protection, and tamper detectors that can detect an attack in progress and take appropriate action. The nRF54L Series provides a complete set of features to comply with current regulatory requirements.
- An additional processor for time-critical tasks: The nRF54L adds a RISC-V processor for handling time-critical tasks is a significant advancement, allowing for more efficient task distribution and potentially reducing the need for external ICs.
Power Consumption and Current Draw Highlights
Following is a diagram showcasing the power efficiency and low-power features of the nRF54L series in various scenarios:
First Impressions and Hands-On Development with nRF54L15 DK
I got my hands on a couple of nRF54L15 DKs a few weeks before its release. From the outside, the packaging looks very familiar and similar to previous DKs (nRF5340 DK, nRF52840 DK, etc.), but the inside is a different story!
For comparison, here’s a closer look at both the nRF54L15 DK and the nRF52840 DK:
Here are a few things that I like about this new DK form factor:
- The DK is more compact (especially compared to the nRF52840 DK), less “busy,” and has a cleaner/simpler layout.
- The DK now features a USB-C interface rather than a Micro-USB interface.
- The DK is ready out-of-the-box for current draw and power consumption measurements using the Power Profiler Kit II (previously, you’d have to cut a PCB trace to prepare the DK for current measurements, but this is no longer the case).
You’ll notice the move away from the Arduino-compatible pin header configuration. The one thing I wish it had (available on previous DKs) is built-in coin cell battery support, though it is not a deal-breaker.
nRF Connect SDK and Development
Getting started with the nRF54L15 DK is a breeze. It’s just like developing for any of the Nordic DKs. It has out-of-box support in the nRF Connect SDK (≥ v2.8.0).
If this is your first time working with a Nordic DK, then I highly recommend following the step-by-step tutorial available in Nordic’s DevAcademy in the nRF Connect SDK Fundamentals Course for installing and setting up the nRF Connect SDK. Ensure that you install nRF Connect SDK version 2.8.0. You can find the installation lesson here.
Once you’ve got everything set up, then you can simply create a project based on any of the existing samples available in the nRF Connect SDK or Zephyr:
The next step is to add a Build Configuration for the nRF54L15 DK:
That’s how simple it is! Basically, it’s just like creating a project for any of the previous Nordic Semiconductor DKs.
Another tool available for the nRF54L series is the Board Configurator Tool, part of the nRF Connect for Desktop application. This tool is unavailable when working with any of the nRF52 series DKs or even the nRF5340 DK.
The tool allows you to update the configuration of the board controller on the nRF54L15 DK. Here’s what this looks like:
Power Consumption Comparison: nRF54L15 vs nRF52840
One of the significant upgrades in the nRF54L series compared to the nRF52 series is more power efficiency, leading to lower power consumption. As you probably know, power consumption is one of the most critical aspects of building a Bluetooth LE-connected device.
Since we are focused on Bluetooth LE functionality, it only makes sense to compare the nRF54L to its predecessor, the nRF52, from the aspect of power consumption and current draw during Bluetooth LE operations.
To make this an “apples to apples” comparison, we’ll use the same sample application, configure it for each board, then run it and compare the current draw in various scenarios.
For measuring the current draw and power consumption, we’ll be using the Power Profiler Kit II, another great hardware tool that Nordic provides that is very cost-effective.
Click to enlarge the image.
The Power Profiler Kit II is a handy hardware tool that allows us to measure current draw from as low as sub-uA and as high as 1A.
Another useful tool available to us without any hardware is Nordic’s Online Power Profiler tool, which allows us to estimate the current draw based on the SoC used and the parameters configured for a Bluetooth Low Energy application.
Here is what it looks like:
Test Setup
For testing, we’ll be using the popular LED Button Service Peripheral sample application, which operates as a simple Bluetooth LE peripheral device, advertising in connectable mode and then allowing a central device to control the LED (turn it on/off) and receive notifications of the Button 0 presses on the DK.
We’ll be running different tests that represent common Bluetooth LE scenarios:
- Advertising mode
- Connection mode
For each of these, we’ll measure the:
- Overall average current draw (averaged over a period of 10 seconds)
- Average current draw in active radio mode
Project Configuration Setup
As part of the standard setup for all test cases, we’ll add the prj_minimal.conf configuration file to the project. This configuration disables several features (e.g., console, serial interface, logging, and more), reducing code size, memory usage, and power consumption.
To do this, add the prj_minimal.conf file to the configuration during the Build Configuration step as shown below:
In addition, we will disable the Scan Response data in the advertising setup to remove any inconsistencies across the various advertising events. We can do so by modifying the following line in main.c (line 236) to set the 4th and 5th parameters to NULL and zero, respectively:
err = bt_le_adv_start(BT_LE_ADV_CONN, ad, ARRAY_SIZE(ad), NULL, 0);
Power Profiler App Setup
The default voltage supplied to the nRF54L15 is 1.8 V, while on the nRF52840 DK, the default voltage is 3.0 V. To have an accurate comparison between the two platforms in each of the tests, we’ll be using the Power Profiler Kit II in the Source Meter mode, enabling the power output, and configuring it to 3.0 V:
Ok, now we’re ready to start running the different tests.
Test Case #1: Advertising mode (100 ms interval)
This is the default setting for the LBS Peripheral example, so no change to the code is needed.
nRF52840 (click images to enlarge):
Overall average current draw: 100.74 uA
Average current draw in active radio mode: 2.77 mA
nRF54L15 (click images to enlarge):
Overall average current draw: 79.02 uA
Average current draw in active radio mode: 2.17 mA
Test Case #2: During the connection state (no user activity)
To run this test, we don’t need to make any code changes. But we’ll be using the nRF Connect for Mobile app to connect to our peripheral (the DK):
nRF52840 (click images to enlarge):
Overall average current draw: 123.52 uA
Average current draw in active radio mode: 1.55 mA
nRF54L15 (click images to enlarge):
Overall average current draw: 84.06 uA
Average current draw in active radio mode: 1.24 mA
Final Thoughts & Next Steps
As you can see from all the tests and current draw measurements, the nRF54L15 outperforms the nRF52840 in all aspects and scenarios. This marks a new era of Bluetooth LE SoCs, enabling devices with a smaller footprint, lower power consumption, longer battery life, and more processing power, all enabled with the help of the powerful nRF Connect SDK.
Resources and Additional Information
Here are some links to resources that you may find helpful: