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A Guide to Nordic Semiconductor's Support of Hardware and Software Updates with Regard to the Bluetooth 4.2 Specification

Nimit Pradhan in Blogs on January 27, 2015

About Nimit Pradhan

Disclaimer – Nordic has yet to confirm the details of hardware and software updates related to the Bluetooth 4.2 specification. This document is intended to give some idea of how Nordic operates in terms of software and hardware revisions.  


Memory Utilization in the nRF51 Series

The nRF51 device is completely flash based. All the executable code, including Nordic’s “Soft Device” (SD) BLE protocol stack and the user’s applications, is programmed in this flash memory.


The soft device is always in the lower region of the flash, using up to 128 kB, and the rest of the upper region of flash is available for user applications.


The BLE protocol resides in the precompiled binary (soft device or “stack”), not in the device itself.


When will there be a hardware revision for 51XXX required to incorporate the new Bluetooth 4.2 features?

Some of the new features in 4.2 may require more RAM memory than what Nordic’s current SD versions use. Nordic just released the third silicon revision of the nRF51 chip and one of the variants Nordic now offers has 32 kB of total RAM, double the 16 kB of total RAM that their previous revisions of silicon had. Much of this is customer driven; as with 4.1, Nordic aims to support the features that the majority of their customers need. So if majority of customers come up with an application that may require more than 32KBRAM/256KB Flash, there may be a need to provide a hardware revision. Nordic tailors new devices to pending market trends and where they believe the technology is heading.


If Nordic comes up with a new chip revision for 51XXX series, will it be hardware/software compatible with the previous hardware/software versions?

At this time, Nordic does not plan to have a new hardware revision of the nRF51 series of devices (which include nRF51822 & nRF51422). The current revision of hardware, revision 3, has a variant with 32 kB of RAM, and that is all they will have. With that said, if Nordic needs to come up with a revision that has more RAM or flash, it may have to be a different silicon, which most likely would not be hardware/pin compatible with the nRF51, but might be software compatible.



  1. Make sure to purchase the nRF51422/51822 32KB option in order to incorporate the new BT4.2 features or any new specifications that may be released by SIG in future.
  2. If a new device or device variant is needed to run certain aspects of the 4.2 or any other stack and has Bluetooth 4.2 functions are enabled, then firmware will not be backwards compatible.


If Nordic comes up with a new software update release, for 51XXX series, will it be hardware compatible with the previous hardware revisions?

The current soft device revisions are only compatible with hardware revisions 2 and 3 of the nRF51 devices, not with hardware revision 1. Please refer to Nordic’s documentation if you are using hardware revision 1 of the nRF51. Nordic intends to keep future soft device revisions compatible with hardware revisions 2 and 3 of the chip.


How can current/new stack/SDK versions be downloaded into the current/newer chip revisions?

Anytime the Bluetooth Special Interest Group (SIG) adopts a new Bluetooth Core version like 4.2, Nordic Semiconductor releases new versions of the soft device as a pre-compiled binary file in hex format, which customers can download from the Nordic website. Customers with a My Page account who have entered the product keys that accompany the current nRF51-DK or the pervious nRF51822 EK get automatic email notifications each time soft device updates are released.


If the user has S110 v.7.0.0 or later, they can update their soft device over the air (over BLE), using Nordic’s Device Firmware Update (DFU) App on the smartphone, along with the bootloader application that runs on the nRF51 to update to the latest version of the soft device.


What are the changes that need to be incorporated in any code developed by customers after the new SDK for BT4.2 comes in?

Customers developing any software on the current soft devices will be able to use their code with future releases of Nordic’s soft device that support 4.2 features. Each of the major releases of Nordic’s soft device, from S110 7.x.y to S110 8.0.0, contain new API functions that allow the user to access the new features, so the user would need to modify their software to take advantage of the new features each time a new soft device is released, and then rebuild their application.


Any major revision of the soft device adds new API functionality and may change some existing API functionality, including deleting an existing API. The number of modifications the customer might need to do to their application can range from significant, if using a very old version of the soft device and want to switch to the most current one (e.g. from S110 v.5.2.1 to S110 v.7.1.0), to very little if they are just switching from the previous major revision to the current one. Any new API functionalities along with any modifications to the existing functionalities are clearly stated in the release notes that accompany the soft device.


The stack comes delivered in a precompiled hex file. The code written now will more than likely be compatible with any new generation of the nRF5 series.


Current compatibility of the current revision 3 chip version with BT4.2 features:

The latest version of the silicon, revision 3, will be able to run several 4.2 features and a precompiled hex file of Nordic’s BLE protocol stack, which is expected be available sometime around the middle of 2015.


Advantage with Nordic

Many of Nordic’s competitors have the BLE protocol stack hard-coded in ROM in their devices, so they cannot easily upgrade to support new BLE features unless they roll out a completely new hardware revision. Nordic is completely flash-based, so customers can use the DFU/bootloader to quickly and easily update to newer versions of the soft device that will release periodically to support newer BLE features. This is a very big competitive advantage for Nordic Semiconductor.


Customers can begin developing their applications with the Nordic Bluetooth Smart/ANT/2.4ghz Development Kit, and easily update the application later when the final stacks and hardware are released.


Contact Symmetry Electronics online or at (310) 536-6190 for more information about Nordic and technical support regarding Bluetooth technologies.



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