July 2020
DT0137 Rev 1
1/7
www.st.com
DT0137
Design tip
How to port an existing project from the BlueNRG-M2SA module
to the BlueNRG-M2SP module
By Salvo Bonina
Purpose and benefits
The BlueNRG-M2 is a Bluetooth® Low Energy system-on-chip application processor based
certified module, compliant with BT specifications v5.0 and BQE qualified. The BlueNRG-M2
module supports multiple roles simultaneously and can act simultaneously as a Bluetooth
master and slave device. The BlueNRG-M2 is based on the BlueNRG-2 system-on-chip and
the entire Bluetooth Low Energy stack and protocols are embedded into the module. The
BlueNRG-M2 module provides a complete RF platform in a tiny form factor. Radio,
embedded antenna and high frequency oscillators are integrated to offer a certified solution
to optimize the time-to-market of the final applications. The BlueNRG-M2 can be powered
directly with a pair of AAA batteries or any power source from 1.7 to 3.6 V.
The BlueNRG-M2 comes in two variants: the BlueNRG-M2SA and the BlueNRG-M2SP.
They have different internal HW configurations, which require a slightly different software
initialization.
Both the BlueNRG-M2SA and the BlueNRG-M2SP modules embed the BlueNRG-2 chipset.
Both the BlueNRG-2 chipset and BlueNRG-M2 modules are BLE5.0 certified (with full
BLE4.2 feature set).
The purpose of this document is to describe all the necessary steps to adapt an existing
project available to the BlueNRG-2 software development kit (SDK) and having as a target
the BlueNRG-M2SA module rather than the BlueNRG-M2SP module.
Main components
BlueNRG-M2
Very low power application processor module for Bluetooth® Low Energy v5.0
July 2020
DT0137 Rev 1
2/7
www.st.com
Description
The BlueNRG-M2SA and BlueNRG-M2SP modules are characterized by a different HW
configuration, as showed in Figure 1 below.
Figure 1 BlueNRG-M2SA vs BlueNRG-M2SP
The HW configuration of the design surrounding the BlueNRG-2 application processor has a
direct impact on the values of the SW data structure used for initializing the BLE radio stack.
In particular, 3 HW-related aspects are relevant:
1. the speed of the high speed crystal (16 or 32 MHz)
2. the presence or absence of an external 32 kHz low speed crystal
3. the presence or absence of a 10 uH inductor to enable the internal switch-mode
power supply (SMPS) HW block
The user application, running on the BlueNRG-2 application processor, must configure 3
preprocessors defined symbols with values reflecting the exact HW design.