ANT Forum

Hi all

The manual ("Interfacing with ANT General Purpose Chipsets and Modules") is not very clear about how RTS and Sleep signals interact.

The manual (Fig2.2) shows RTS is deasserted for 50uSec when a correctly formatted message is received.

Fig2.3 does not show this pulse which is where I am getting confused.

My reading of figure 2.3 is that that RTS is permanently deasserted (I guess it is deasserted once a correctly formatted message is received) until the sleep pin is toggled. Is that right???? Or is fig 2.3 drawn incorrectly and there should be a 50uSec pulse after each correct message??

Is there a spec for the timing from Sleep going low to RTS going low?
Is there a spec for the timing from a message being determined to be correct and RTS being pulsed?

Thank you for your time.
Julian      

Hi Julian,

The figure is slightly incorrect in that the RTS is always 50us for the pulse. But there is no exact timing that you can wait for RTS.

The ANT Power States Application Note discusses how sleep modes work for the AP2/AT3 modules. Page 4 discusses the relationship between the sleep line and RTS.

The ANT+ Embedded Reference Designs have example code for doing serial communication with a Network Processor using an MSP430 (serial.c), but it should be similar for most platforms. The message flow for sending a messages goes as follows:

1. De-assert sleep.
2. Wait until RTS de-asserts.
3. Send your message.
4. Wait for RTS to assert.
5. Wait for RTS to de-assert.
6. Repeat 3-6 for additional messages.
7. Re-assert sleep.

Cheers