ANT Forum

Hello,

Refer section 5.3 Synchronous serial interface in nRFAP2 Product Specification select bit flow timing mode.

The 1st SYNC byte get from AP2 is 0xA4, Message ID is 0x6F and data is 0x00.

Why not the 1st SYNC byte is 0xA4 not 0xA5?

The host MCU need how to process this 0x6F message and the following Control Message how to send to AP2?

How to get the SYNC byte 0xA5?      

You can refer to the ANT Message Protocol and Usage document to interpret the message you are seeing. 0x6F is the Startup message, and it is the first message you will see after power up/reset when using AP2. After receiving this first message, you should be able to send your first message to ANT (i.e. sync byte 0xA5).

http://www.thisisant.com/pages/developer-zone/ant-protocol-and-usage