User's Manual

CONFIDENTIAL

3. UART COMMUNICATION PROTOCOL PACKETS

3.1. Packets

The uart protocol packets contain data that will be used as an interface between the HRM3300 and the

equipment console. A maximum of twenty four bytes and a minimum of eight bytes are used during Uart

communication.

Fletcher checksum reference: https://en.wikipedia.org/wiki/Fletcher%27s_checksum

For 5kHz analog strap, the name to be transmitted will be “5kHz HRM”.

Below is the UART packet:

A response bit when set means the receiver is obliged to response acknowledgement when package is

received from the transmitting Uart port

START

COMMAND

PACKET LEN CHECK

SUM

RESPONSE

BIT

CLASS SUB DATAx

Type Size in bytes Description

START COMMAND 1 Start byte

PACKET LEN 1 Number of bytes in a packet

CHECK SUM 2 Fletcher checksum

RESPONSE BIT 1 Response bit

CLASS 1 Packet Class type

SUB CLASS 1 Packet sub-class type

DATA

BLE advertising name and BLE address with “0x1F” separator

between name and address

8 5Khz HRM name

2 ANT+ ID

1 Other data

3.2. Example of Sending Packets Equipment Console

Usage:

Sending packet name to equipment console

Format:

[Start Command]

[Packet Size]

[Fletcher check sum low byte]

[Fletcher check sum high byte]

[Response bit]

[Class]

[Sub Class]

[Name 1

byte]