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18 January 2011 08:40 PM

arknav.fae Newbie

Total Posts: 5

Joined 2009-10-07

Dear Admin,

We've been working on UART and SPI on AP2 module.

Attached is the figure from logic analyzer:
Interface is using UART, async. mode.

First signal is Rx (ANT receives from MCU).

Second signal is TX (ANT transmits to MCU).

Third signal is RTS (Request to send) which is a ready signal of ANT when RTS = 0.

Question is WHY RTS takes so long to ready after ANT received 9 burst transfer package.

It takes almost 16ms.

What happened during this period?????
[img size=150][/img]
Another question is in the some period ANT transmits data to MCU.

Could you tell me when ANT transmits data to MCU?

Regards

19 January 2011 11:13 AM #1

alejandra Moderator

Total Posts: 662

Joined 2012-10-09

It seems like the attachment of the post is missing. What is your channel period?

ANT will start transmitting a burst until the next channel period. The AP2 can buffer up to 9 packets, so you can send 9 packets over the serial port until the buffer is filled, and then ANT will raise RTS to indicate the MCU to stop sending packets. You can see a diagram illustrating this here, although the figure is for AP1, which can only buffer 2 packets.
http://www.thisisant.com/component/option,com_fireboard/Itemid,146/func,view/id,139/catid,25/

ANT will send an EVENT_TRANSFER_TX_START when the burst begins. You can find more details on the messaging involved in bursting in Section 9.5.5.3 of the "ANT Message Protocol and Usage" document
http://www.thisisant.com/products/data-sheets-brochures

19 January 2011 08:17 PM #2

arknav.fae Newbie

Total Posts: 5

Joined 2009-10-07

Hi Alejandra,

i try to attach the picture again. [img size=684]http://www.thisisant.com/images/fbfiles/images/UART_burst.JPG[/img]

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