ANT+ Protocol translator

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04 May 2021 05:35 AM

Aba Newbie

Total Posts: 2

Joined 2021-04-01

Dear all,

I put you in the situation, hoping that someone knows a similar case and can help me.

I am developing a project where it is intended to transmit the sensor data of an electric bike (cadence, power and speed) using the ANT + protocol and then use indoor training simulators (for example Zwift).

These sensors are connected by an ASI controller (Electric Motor Controllers | Accelerated Systems Inc.) and we know how to gather the necessary data through the controller. It is intended to use an Arduino board to create a message in the ANT + protocol and transmit it via bluetooth.

At this point, I would like to ask you if you know of a similar case where someone intends to transmit data from bicycle sensors using the ANT + protocol. If you can help me, I would need to know what structure a complete ANT + message has. I have reviewed the profile of the sensors, but these are a bit complex to understand and I can't quite understand the array of bits that has to be transmitted and what each bit means. If anyone could help me understand this protocol structured by Data Pages, I would be forever grateful.

I have SimulANT + and two USBs, with which I have tried to figure out how a message is structured, but to no avail.

Thank you very much in advance, I hope someone has knowledge to help me a bit.

Greetings,

Aba

10 May 2021 08:48 AM #1

haighi Administrator

Total Posts: 370

Joined 2012-06-27

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You cannot transmit ANT+ data over Bluetooth. It must be transmitted over ANT.

Zwift works with the ANT+ Fitness Equipment, ANT+ Bicycle Power, and ANT+ Speed and Cadence profiles from https://www.thisisant.com/developer/resources/downloads/#documents_tab These. documents define the data format.

I recommend reading https://support.zwift.com/en_us/ant-and-ble-overview-B1S1BVgr and https://zwiftinsider.com/getting-started-power-meter/

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Ian Haigh

11 May 2021 03:32 AM #2

Aba Newbie

Total Posts: 2

Joined 2021-04-01

PM

Hi Haighi,

First of all, thank you very much for your answer.

I can't quite understand why I can't transmit data in ANT + protocol via bluetooth if I know the structure of the message. I would really appreciate knowing why they are incompatible.

My idea is with my own sensors, to take the data of interest and use it to transmit the ANT + message following the format of each profile. If there is a simpler method I am open to opinions.

Thanks again for the reply.

11 May 2021 03:41 PM #3

haighi Administrator

Total Posts: 370

Joined 2012-06-27

PM

ANT+ profiles are built on top of the ANT protocol. The receiver and transmitter must both be setup with ANT radios, and the ANT+ profile defines how exactly the radio must be configured, and how messages can be parsed.

This is similar to how FTMS in Bluetooth is built on top of the Bluetooth Core Specification 4.0 or later, and GATT.

If you aren't following ANT+ FE-C (using ANT) or FTMS (with Bluetooth 4.0 and GATT), then Zwift will not be setup to receive from you. Note: Zwift works with other ANT+ profiles and Bluetooth services as well, but I am focusing on the two primary here to keep the explanation simpler.

Think of ANT and Bluetooth 4.0 being basic definitions like "here are the characters in our alphabet and words we create from them". ANT+ FE-C and Bluetooth FTMS are next level definitions like "here are the words strung together into a sentence in our language". If ANT is the 26 character English alphabet and words, and Bluetooth is the Cyrillic script alphabet and Russian words, then ANT+ FE-C could be thought of as rules describing the sport of soccer written in English and Bluetooth FTMS as rules describing the sport of soccer in Russian. You can have the same rules, but you as the speaker have to match the characters and language of who you are talking to. Zwift would be someone who reads English and Russian.

The idea you are talking about using ANT+ structured data over Bluetooth would be like trying to talk to Zwift using English sentences written with Cyrillic characters. Zwift won't understand.

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Ian Haigh

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