ANT Forum

Hello everybody
I am developing an ANT+ HRM receiver using CC2570 chip from TI working in asynchronous serial interface.
To make de PCB, I followed SWRS095A datasheet (page 13):
http://www.ti.com/lit/ds/swrs095a/swrs095a.pdf

Using values described in reference design:
http://www.ti.com/litv/zip/swrc225

Now I am using a serial RS232 interface connected to a PC to debug all the communication and everything seems to work ok.
I have a Garmin Premium Heart Rate Monitor (Soft Strap).

First of all I tested all the communication with Garmin ANT USB Stick and ANTware II software. After that, I am trying to send all necessary messages to configure CC2570 as the same way that I used in ANTWare II.

When I switch on the power supply, I receive the following message:

RX: a4 01 6f 00 ca (startup)

Then I send all these information:

1 - ASSIGN CHANNEL (Ch 0)
TX: a4 03 42 00 00 00 e5
RX: a4 03 40 00 42 00 a5

2 - SET CHANNELID
Option 1 (trans type 0x00)
TX: A4 05 51 00 00 00 78 00 88
RX: a4 03 40 00 51 00 b6

Option 2 (trans type 0x01)
Tx: A4 05 51 00 00 00 78 01 89
Rx: a4 03 40 00 51 00 b6

Option 3 (trans type 0x01, dev number 0x267, 615 in decimal)
Tx: a4 05 51 00 67 02 78 01 ec
Rx: a4 03 40 00 51 00 b6

3 - NETWORK KEY
TX: a4 09 46 00 xx xx xx xx xx xx xx xx xx
RX: a4 03 40 00 46 00 a1

4 - CHANNEL PERIOD (0x1f86, 8070 in decimal)
TX: a4 03 43 00 86 1f 7d
RX: a4 03 40 00 43 00 a4

5 - CHANNEL RF FREQUENCY (0x39, 57 in decimal)
TX: a4 02 45 00 39 da
RX: a4 03 40 00 45 00 a2

6 - OPEN CHANNEL (Ch 0)
TX: a4 01 4b 00 ee
RX: a4 03 40 00 4b 00 ac

After some seconds…
RX: a4 03 40 00 01 01 e7 a4 03 40 00 01 07 e1 (timeout and close channel)

Before testing hardware I would like if than I am doing is ok. I tried to repeat all 6 steps for every option (step 2), but I always have the timeout.

I tried to change TX power to min or max value without other result:

TX MAX POWER
TX: a4 02 60 00 04 c2
RX: a4 03 40 00 60 00 87

TX MIN POWER
Tx: a4 02 60 00 00 c6
Rx: a4 03 40 00 60 00 87

Furthermore I tried to reset the chip, change the search timeout and ask for device parameters:

Tx: a4 02 4d 00 51 ba
Rx (from option 3, step 2): a4 05 51 00 67 02 78 01 ec

It seems that I can “talk” correctly to the chip but I can't receive any information from de HRM Strap) and I tried several times with ANTWare II and works OK.

Am I doing it correctly? Any suggestion will be appreciated

Thank you so much.      

Hello,

It looks as though your channel is being set up correctly to receive from an ANT+ HRM. Option 1 should be sufficient for you to receive data from any HRM in the area. Also, setting the transmission power for a receiving device will not really do anything, it is used for transmitting devices. Just to confirm, you say that you can receive okay from the HRM from ANTware II?

Kassandra      

Hello Kassandra, thank you for the reply

Yes I can, first of all I tested all the configurations using Garmin ANT+ USB stick, ANTWare II software and Garmin Premium Heart Rate Monitor (Soft Strap), and I saw all page formats, decoded my heart rate information, etc.

After that, I made a PCB using CC2570RHAT chip but it always sends me a timeout and close channel commands. I tried to resolder de chip, change it to another cc2570 without solution.

I have read all these information:



- ANT+ Device Profile HEART RATE MONITOR.

- ANT Message Protocol and Usage

- ANTware II User’s Guide

- Interfacing with ANT General Purpose Chipsets and Modules

- SWRS095A (cc257x datasheet)

- CC257X EM Discrete Reference Design

But I can’t find any solution.

Any ideas? Thank you so much.      

Hello,

Since it appears as though the serial communication is working correctly, it might be time for you to look at your hardware. One thing I can suggest is to configure your hardware to be a simple broadcasting master device and use ANTware II to try and receive messages from it. This would allow you to run your hardware without the timeout problem. If you have a bad antenna, or a crystal out of tolerance you might not be able to pair with it on ANTware II or you might get many Rx Fail messages.

Keep me posted on your progress,

Kassandra      

Hello again, while I am doing your suggestion, I attached all the components references involved in Rx/Tx and oscillators:
- Antenna (YAGEO (PHYCOMP), ref: CAN4311153002451K):
http://www.farnell.com/datasheets/48853.pdf
- Xtal1 (RALTRON, ref: R26-32.768- 12.5):
http://www.raltron.com/products/pdfspecs/crystal_r38_26_145.pdf
- Xtal2 (Multicomp, ref: HC49U-32-20-30-60-00-AT3):
http://www.farnell.com/datasheets/321153.pdf
- 12 and 18 pF ceramic capacitors C0G / NP0, ± 5%
- 1 pF ceramic capacitors C0G / NP0, ± 0.25%
- Inductor 1 nH
- Inductor 2 nH, ± 0.2%, 0.08 ohm, 700 mA, resonant freq 6.9 GHz (ref: 744761020A)
http://www.farnell.com/datasheets/426778.pdf
- Inductor 1 nH, ± 0.3%, 0.1 ohm, 500 mA, resonant freq 6 GHz (ref: MCFT000037)
http://www.farnell.com/datasheets/360119.pdf
- Inductor 3.3 nH, ± 0.3%, 0.13 ohm, 300 mA, resonant freq 6 GHz (ref: HK21253N3S-T)
http://www.farnell.com/datasheets/1500426.pdf
I chose them looking for similiar characteristics basing CC257X EM Discrete Reference Design excel document.

I am going to test your suggestion, thank you so much.