UM1870 datasheet(33/58 Pages) STMICROELECTRONICS

33 / 58 page

DocID027602 Rev 1

33/58

UM1870

BlueNRG-MS sensor profile demo

The software development kit contains an example, which implements a proprietary

Bluetooth profile: the sensor profile. This example is useful for building new profiles and

applications that use the BlueNRG-MS network processor. This GATT profile is not

compliant to any existing specification. The purpose of this project is simply to show how to

implement a given profile.

This profile exposes two services: acceleration service and environmental service.

Figure 13 shows the whole GATT database, including the GATT and GAP services that are

automatically added by the stack.

One of the acceleration service’s characteristics has been called free-fall characteristic. This

characteristic cannot be read or written but can be notified. The application will send a

notification on this characteristic (with value equal to 0x01) if a free-fall condition has been

detected by the LIS3DH MEMS sensor (the condition is detected if the acceleration on the 3

axes is near zero for a certain amount of time). Notifications can be enabled or disabled by

writing on the related client characteristic configuration descriptor.

The other characteristic exposed by the service gives the current value of the acceleration

that is measured by the accelerometer. The value is made up of six bytes. Each couple of

bytes contains the acceleration on one of the 3 axes. The values are given in mg. This

characteristic is readable and can be notified if notifications are enabled.

Another service is also defined. This service contains characteristics that expose data from

some environmental sensors: temperature, pressure and humidity(c). For each

characteristic, a characteristic format descriptor is present to describe the type of data

contained inside the characteristic. All of the characteristics have read-only properties

An expansion board with LPS25H pressure sensor and HTS221 humidity sensor can be connected to the

motherboard through the expansion connector (F in Figure 2). If the expansion board is not detected, only

temperature from STLM75 will be used.

UM1870 датащи(PDF) 33 Page - STMicroelectronics