Mantracourt B24, B24-SSBX-A Technical Manual

B24 Telemetry Technical Manual

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B24

Bluetooth Telemetry System

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Introduction / Overview .............................................................................................................................................3

Advertising Operation ............................................................................................................................................................................... 3

Connected Operation ................................................................................................................................................................................ 3

B24 Advert Format ......................................................................................................................................................4

Local Name .................................................................................................................................................................................................... 4

Manufacturer Specific Data .................................................................................................................................................................... 4

Format ID ................................................................................................................................................................................................... 4

Status .......................................................................................................................................................................................................... 4

Units ............................................................................................................................................................................................................. 5

Data Tag ..................................................................................................................................................................................................... 5

Data.............................................................................................................................................................................................................. 5

Bluetooth Connected Mode ......................................................................................................................................6

Telemetry Configuration Service .......................................................................................................................................................... 6

Data Rate ................................................................................................................................................................................................... 6

Resolution ................................................................................................................................................................................................. 6

Battery Threshold ................................................................................................................................................................................... 7

View PIN ..................................................................................................................................................................................................... 7

Serial Number .......................................................................................................................................................................................... 7

Battery Value ............................................................................................................................................................................................ 7

System Zero .............................................................................................................................................................................................. 7

Configuration Pin ................................................................................................................................................................................... 8

Model Name ............................................................................................................................................................................................ 8

Firmware Version .................................................................................................................................................................................... 8

Telemetry Data Service ............................................................................................................................................................................. 9

Data Value ................................................................................................................................................................................................. 9

Data Units .................................................................................................................................................................................................. 9

Telemetry Calibration Service ............................................................................................................................................................. 10

Sensitivity Range ................................................................................................................................................................................. 10

Coefficient (@Index)........................................................................................................................................................................... 10

Linearisation Index .............................................................................................................................................................................. 10

Linearisation Repeat ........................................................................................................................................................................... 10

Linearisation Points ............................................................................................................................................................................ 11

Base Value .............................................................................................................................................................................................. 11

Base Units ............................................................................................................................................................................................... 11

Data Gain ................................................................................................................................................................................................ 11

Data Offset ............................................................................................................................................................................................. 11

Calibration PIN ..................................................................................................................................................................................... 11

Calibration Units .................................................................................................................................................................................. 11

Advanced Index ................................................................................................................................................................................... 12

Advanced Data ..................................................................................................................................................................................... 12

Connection Security ................................................................................................................................................................................ 12

Operation Examples ................................................................................................................................................. 13

Decoding Data with View PIN ............................................................................................................................................................. 13

Connection ................................................................................................................................................................................................. 14

Reading Data ............................................................................................................................................................................................. 14

Examples: ................................................................................................................................................................................................ 14

Writing Data ............................................................................................................................................................................................... 15

Calibration .................................................................................................................................................................................................. 16

Unit Conversion ........................................................................................................................................................................................ 18

Appendices ................................................................................................................................................................ 19

Appendix A - Bluetooth UUID Quick Reference .......................................................................................................................... 19

Appendix B - Units .................................................................................................................................................................................. 20

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Appendix C - Advanced Parameters ................................................................................................................................................ 23

Appendix D – Filter .................................................................................................................................................................................. 25

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Introduction / Overview

The B24 Bluetooth Telemetry range provides access to quality measurements on a mobile platform such as a

phone or tablet. The delivery mechanism is ‘Bluetooth Low Energy’ (Also known as ‘Bluetooth Smart’ or BLE)

which utilises the flexibility and availability of Bluetooth receivers while maintaining the low power requirements of embedded systems. B24 is built upon two complimentary principles of BLE, broadcast advertising data which enables users to deliver the same data to multiple receivers simultaneously and low power connections which can be used in a point to point system. B24 is available in OEM bare board formats and with environmentally sealed enclosure with integrated battery holder. This manual provides details of data delivery and configuration mechanisms available to system developers intending to implement their own configuration and monitoring application. There are also worked examples for calibration, data delivery and unit conversion.

Advertising Operation

The advertising mode of operation enables B24 modules to broadcast measurement data to multiple locations without retransmission. The advert is a new operational mode within ‘Bluetooth Low Energy’ and facilitates the delivery of data without a connection. This mode of operation is useful in ‘many to many’ and ‘one to many’ use cases.

Connected Operation

The connected operational mode enables Bluetooth Low Energy devices to connect directly to the B24 module. A single mobile device can be connected to multiple B24 transmitter modules simultaneously. This mode has a dual purpose as it may be used to monitor data and configure the device. When it is used for the delivery of data the application can register to receive notification updates when the status and engineering unit value changes. This mode of operation is useful in ‘one to one’ and ‘many to one’ use cases.

One to One

Many to One

One to Many

Many to Many

Mantracourt Electronics Limited B24 Telemetry Technical Manual

B24 Advert Format

The Bluetooth advert is the primary operating role of this product. The advertising packet is broadcast periodically at a configurable rate. The full list of configurable items will be discussed with the section on the

Bluetooth Connected Mode section.

The transmission of the advert and the corresponding data is also split into subtopics. The Bluetooth Special Interest Group has provided specific details on the format and content of each advert type. The B24 advert is constructed from the connection flags (advert type 0x01), manufacturer specific data (advert type 0xFF) and the device local name (advert type 0x09). Provision has been made for future developments and extensions of the manufacturer specific data to include other data formats but for the moment only one will be discussed.

The basic format and structure of the B24 advert packet can be observed using a simple BLE scanner. There are many available for android and Apple iOS (A good example is the nRF Connect app).

Local Name

The local name is part of the standard set of data defined by the Bluetooth SIG. The module name that is supplied will depend upon the length of the name given to the product. The length of the name has an impact upon the rest of the data packet and as such should be kept short where possible. The advert is sent with advert type 0x09 as an ASCII character array. The local name is factory configured to the default value “B24”. The name field in the device has a maximum length of eight characters. The advert mechanism will send the full name of the device stored in the EEPROM.

Manufacturer Specific Data

The manufacturer specific data is sent with advert type 0xFF. The current format carries data for a single sensor. The format of this section is shown in Table 1. By default a hash is applied to the data broadcast from the unit and this will be applied to all bytes after the first data tag pair (Shown in bold). An example decoding the advert is provided later in this section. The measured data is a fixed length parameter in the advert of 4 bytes. This will follow the standard Float format (IEEE 754). N.B The status byte, units, data and the terminating data tag pair are encoded. N.B The format shown in Table 1 is indicative of the bytes transmitted. Some monitoring applications and APIs do not present the length field to the user.

Name

Size

Description

Length field

1 byte

Part of the Spec

Advert Type

1 byte

0xFF (Manufacturer Specific Data)

Company ID

2 bytes

0x04C3

Format ID

1 byte

Data Tag

2 bytes

Module ID

Status

1 byte

Units

1 byte

Data

4 bytes

Floating point data (IEEE 754)

Data Tag

2 bytes

Used to verify decoding

Data Tag

2 bytes

Used to verify decoding

Table 1: B24 Advert Format

Format ID

The format ID uniquely identifies the format of the rest of the packet. This allows for future expansion of the format for other purposes without impacting legacy equipment. This is currently set to 1.

Status

The status byte indicates status using the bit values and is defined in Table 2.

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Bit

Name

Description

Reserved

Digital Input

Digital Input Active Flag

Batt Low

Low battery warning flag

Fast Mode

Unit is currently operating in “Fast” data rate mode.

OverRange

Input is out of sensitivity or display range

NotGross

A tare value has been applied.

Integrity

Sensor integrity Error

Shunt Cal

Shunt Cal active

Table 2: Status Byte format.

Units

The units for the module are sent as a single byte. The definition of these groups and values is in Appendix B -

Units. This table identifies the group within which a simple translation can be applied and the symbol that should

be displayed on the screen. It also includes the conversion factors that may be used to convert within a group.

Data Tag

The Data tag is defined as a 2 byte hexadecimal number. This number is specific to the sensor and configurable in the unit. The default value is assigned in the factory prior to shipping and indicated on the label. The data tag is repeated in the transmission packet in order to facilitate the extraction of the encoded data. Please refer to the

Error! Reference source not found.section.

Data

The data is a fixed length field of four bytes. All data is transmitted as a standard Float format (IEEE 754).

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Bluetooth Connected Mode

The B24 profile provides access to services and characteristics used to configure and receive measurements. They are all custom 128-bit Unique ID’s. The only generic profiles that will be enabled in the module are the mandatory Generic Access and Generic Attribute profiles. Please refer to documentation supplied by the Bluetooth SIG (Special Interest Group) for a description of the characteristics provided by these services. All the data carried over Bluetooth is received by the host application as a byte array. The data format on a read is described in Appendix A.

It is recommended that all writes to characteristics use the Write With Response method

rather than Write With No Response. This allows time for indexed characteristics to update internally.

Telemetry Configuration Service

The telemetry Configuration service provides access to general configuration parameters. The characteristics within this service are likely to be required by technicians and installers. This service is identified by its unique 128-bit ID. This is: a970fd30-a0e8-11e6-bdf4-0800200c9a66

Data Rate

The data rate defines the period between taking a measurement. The advert broadcast is also linked to this parameter. The data rate is specified in ms as the period between measurements. The value entered may be between 0 and 10000. N.B. Bluetooth does not allow adverts to be broadcast more often than every 80 ms. As such, values between 1 and 79 will be accepted as a value of 80. A value of 0 will stop data acquisition. However it will not stop the advertising profile. The adverts will be broadcast once every 5 seconds with a value of NaN and the status byte will be set to 0xFF (255 decimal). This characteristic is identified by its unique 128-bit ID. This is: a970fd31-a0e8-11e6-bdf4-0800200c9a66

Resolution

The number of samples used to produce a measurement is configurable. The resolution that can be achieved is given in Table 3. The number of samples used to obtain a measurement will directly impact upon the battery life of the product as it changes the time required to make a measurement. The measurement time is the time that the Strain Bridge input is being sampled. If the Data Rate is set to less than 200mS then the Resolution parameter is limited to a maximum of 16.

Resolution Parameter

Bits Noise Free @ 2.5 mV/V

Measurement time

Effect on Battery Life 8 (default)

14.25

20 ms

Maximum

15.25

32 ms

75%

56 ms

50%

16.5

80 ms

37%

16.75

104ms

30%

Table 3: Resolution Table.

This characteristic is identified by its unique 128-bit ID. This is: a970fd32-a0e8-11e6-bdf4-0800200c9a66

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Battery Threshold

The battery threshold value is a floating point number specified in volts. The default value (2.5 V) is designed for use with a pair of alkaline cells. The minimum operating voltage is 2.3 V. This characteristic is identified by its unique 128-bit ID. This is: a970fd33-a0e8-11e6-bdf4-0800200c9a66

View PIN

The View PIN is used to encode the broadcast data such that other users are not able to decode and read the values. This is applied on top of the normal encoding and allows the user to hide individual systems. The View PIN is an array of four characters. The full description of the usage of the data in this characteristic is given in the

Operation Examples section titled Decoding Data with View PIN.

This characteristic is identified by its unique 128-bit ID. This is: a970fd34-a0e8-11e6-bdf4-0800200c9a66

Serial Number

The serial number is set in the factory and cannot be changed by the user. This characteristic is identified by its unique 128-bit ID. This is: a970fd35-a0e8-11e6-bdf4-0800200c9a66

Data Tag

The data tag is used to identify the transmitter. It is set in the factory and indicated on the label. The parameter is writable and as such may be set to any 32 bit number. This characteristic is identified by its unique 128-bit ID. This is: a970fd36-a0e8-11e6-bdf4-0800200c9a66

Battery Value

The battery value contains the latest measurement of the battery voltage. The parameter is a read only float. This characteristic is identified by its unique 128-bit ID. This is: a970fd37-a0e8-11e6-bdf4-0800200c9a66

System Zero

The system zero is a floating point value that is stored in non-volatile memory. This value is subtracted from the final value on each measurement. It is stored as a floating point number.

This value should not be used as a live tare (i.e. for each new measurement). It is designed

such that the zero can be applied at the point of installation and stored in non-volatile memory rather than written multiple times per day. There are 100,000 write cycles on the non-volatile memory before it is worn out.

The system zero value will be converted automatically if a unit conversion is made to the module. This will have no effect if the Linearisation Points is zero. This characteristic is identified by its unique 128-bit ID. This is: a970fd38-a0e8-11e6-bdf4-0800200c9a66

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Configuration Pin

The Configuration PIN controls the access to the device. It must be written to as the first action after connecting to the unit. Until it has verified the value of the Configuration PIN it will always read zero then disconnect the link. Attempting to access any parameter prior to entering a valid Configuration PIN will result in disconnection of the link. The Configuration PIN number is a user settable unsigned 32 bit integer. The default value is 0. This characteristic is identified by its unique 128-bit ID. This is: a970fd39-a0e8-11e6-bdf4-0800200c9a66

Model Name

The model name is a factory set parameter that indicates the type of acquisition module that is present. It is a string of characters that identify the module. Currently there is only one. This is formatted as: “B24-SSBX-A” B24 – B24 range SSB - Strain Sensor Bridge X -OEM Module A -Standard Variant

This characteristic is identified by its unique 128-bit ID. This is: a970fd3a-a0e8-11e6-bdf4-0800200c9a66

Firmware Version

The firmware version is a read only parameter. The value is stored as a float and updated when new firmware is generated. This characteristic is identified by its unique 128-bit ID. This is: a970fd3b-a0e8-11e6-bdf4-0800200c9a66

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Mantracourt B24, B24-SSBX-A Technical Manual

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