ANT Forum

What are you using as a receiver?

When you say you get data at 1 second intervals, do you mean any data or specifically speed? You should be receiving a page approximately every 0.25 seconds. Note that some may be lost due to poor RF conditions. If you are receiving fewer that 4 pages per second, I recommend moving your receiver closer to the trainer.

Section 8.3 of the profile document deals with suggested transmission patterns, and 10.1.1 the minimum transmission rate. You can see from table 10-1 that some devices may only be transmitting speed at approximately 1 second intervals.

If the speed is only updated once every 5 seconds it is likely dictated by the manufacturers implementation.

I recommend using SimulANT+ to confirm the transmission pattern and update rate used by your trainer. You can also use SimulANT+ to simulate a trainer to test your implementation.

Ian

     

Ah yes that makes sense as a possible transmission pattern. Note that from page 26 you can get speed if you have the user configure wheel size (see section 8.10.2). See section 8.6.8.5 for details on the speed calculation. Note that this speed may vary slightly from the value in page 16.

Ian      

You are missing a byte for wheel period.

The fact that you got a negative value leads me to believe you are not handling the rollover of event count properly.

Additionally, (3600 / 1000) is likely evaluating to 3 assuming you are using unsigned integer types. Similar integer division issue may apply to division by 2048.

Ian      

Wheel period is 2 bytes in size.

Ian      

See 8.6.8.3.1 for notes on the case where the wheel isn't rotating. You should be switching to 0 speed based on data page 16 while event count is unchanging.

16 bit unsigned integer for wheel period. data[3] is the lsb and data[4] is the msb.

Ian      

based on https://docs.microsoft.com/en-us/dotnet/api/system.bitconverter.touint16?view=netframework-4.8 you need to swap wheelPeriodArray[0] and [1]. [0] should be data[3]

Ian