RTOS/CC1310: Constant carrier mode for CC1310, or way to increase transmit duty cycle

Ben Kneale

Part Number: CC1310
Other Parts Discussed in Thread: CC1101

Tool/software: TI-RTOS

Hello,

I'm currently developing on the CC1310 launch pad and the goal is a simplex RF link running at the highest possible speed. One CC1310 is always transmitting and the other receiving.

I'm trying to optimise the RF air time, or even have the transmitting CC1310 left in a constant carrier mode. To illustrate, I'm using the CC1310 rfPacketTx example in proprietary packet mode and I post two commands in back-to-back, however the CC1310 appears to turn off the transmitter between commands.

cmdHandle = RF_postCmd(rfHandle, (RF_Op*)&RF_cmdPropTx, RF_PriorityNormal, NULL, 0);
cmdHandle = RF_postCmd(rfHandle, (RF_Op*)&RF_cmdPropTx, RF_PriorityNormal, NULL, 0);

I have this transmitting into my measurement device and its showing two transmit events:

Is there a way using the SDK or driver to eliminate the pause between transmissions? Or perhaps have the CC1310 in a constant carrier mode where it simply sends preamble when there are no RF commands to be executed?

Thanks,

Ben

over 8 years ago

0 TER over 8 years ago

TI__Guru**** 317180 points

If you want to send a CW or a repeated pattern, take a look at the CMD_TX_TEST command (23.3.3.1.8 in www.ti.com/.../swcu117g.pdf)

0 Ben Kneale over 8 years ago in reply to TER

Prodigy 100 points

My primary objective here is to eliminate the gap between data transmissions. Secondary to this would be have the constant carrier feature, which would interleave my actual user data as a high priority and then default back onto a repeated pattern, just to keep the carrier up.

0 Siri over 8 years ago

TI__Guru* 86731 points

Hi Ben

To send packets back to back you can use the advanced TX command. Please see https://e2e.ti.com/support/wireless_connectivity/proprietary_sub_1_ghz_simpliciti/f/156/p/594277/2184712?tisearch=e2e-sitesearch&keymatch=%20user:2957#2184712

BR Siri

0 Ben Kneale over 8 years ago in reply to Siri

Prodigy 100 points

Thanks Siri I'll have a look.

0 Leonid A. over 8 years ago

Expert 1630 points

Hi Ben,

to eliminate the pause between transmissions you must:

1. Send only one packet, not two.

2. Configure Rf driver not add CRC.

3. Calculate CRC manually.

3. Build the packet to send as following:

1st Packet Length

1st Packet Data

1st Packet CRC

Preamble

Sync Word

2nd Packet Length

2nd Packet Data

2nd Packet CRC

4. Configure CMD_PROP_TX pktLen equal to total packet length

Leonid

0 Ben Kneale over 8 years ago in reply to Leonid A.

Prodigy 100 points

Hi Leonid,

Thanks for the info. The ultimate goal is to eliminate gaps between all packets, so an infinitely long transmission. Is this technique able to achieve this?

Cheers

Ben

0 Siri over 8 years ago in reply to Ben Kneale

TI__Guru* 86731 points

Hi Ben

This is what I do in the code I referred you to in an earlier post. In that example RF_cmdPropTxAdv.pktLen = 0, meaning unlimited packet length. In the example I stop sending after having sent the same packet 100 times (by setting the txQueue.pLastEntry = txQueue.pCurrEntry) but in theory you can continue as long as you want.

Siri

0 Leonid A. over 8 years ago in reply to Siri

Expert 1630 points

Hi Siri,

thanks for explanation.

Leonid

0 Ben Kneale over 8 years ago in reply to Siri

Prodigy 100 points

Hi Siri,

Thanks for that. I have the example going for continuous transmission. Is it possible to have the RF core append CRCs to each packet sent within the transmit queue?

When I use

RF_cmdPropTxAdv.pktConf.bUseCrc = 1;

It appears to only append a CRC to the final packet in a transmission.

Failing that, is there a library function I can use to manually calculate the CRC that the RF core uses?

Cheers

Ben

0 Siri over 8 years ago in reply to Ben Kneale

TI__Guru* 86731 points

Hi Ben

When using this approach you need to calculate the CRC is SW. the default CRC is the same as the one used for the CC1101 and a SW implementation of this CRC is described here: http://www.ti.com/lit/swra111

BR
Siri

0 Aliaksei Khadakouski over 8 years ago

Prodigy 175 points

I am sorry for offtop, but can you tell what tool did you use to make transmit measurements (how did you get provided TX graph)? Thx

0 Ben Kneale over 8 years ago

Prodigy 100 points

Thanks again Siri.

Aliaksei: The tool is GNU Radio, I was using an RTL-SDR as the RF source.

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RTOS/CC1310: Constant carrier mode for CC1310, or way to increase transmit duty cycle