CCS/CC1350: CC1350: Packet interval & Payload length?

Azor_Ahai

Part Number: CC1350

Tool/software: Code Composer Studio

Hi,

I am doing the PacketTx and PacketRx examples from Resource Explorer and in the code it says:

/* Packet TX Configuration */
#define PAYLOAD_LENGTH      30
#define PACKET_INTERVAL     (uint32_t)(4000000*0.5f) /* Set packet interval to 500ms */

QUESTION1: Payload length is just user data or also the preamble+syncword+USERDATA+crc?

QUESTION2: Interval of 500ms is I suppose the time between 2 packets being send one after the other. Is that interval necessary? Because it is in

user´s interest that there is as little as possible latency when sending packets.

Thank you!

over 6 years ago

0 Siri over 6 years ago

TI__Guru* 81091 points

Payload length 30 means that the length byte is set to 30 and that there are 30 bytes following the length byte. Preamble, sync and CRC are in addition. You can off course decrease the interval in-between packets, but if you for example want to receive the packets you send with SmartRF Studio, you cannot set the interval too short. In a user application, what you must take into consideration is the processing time you need on the receiver side.

0 Azor_Ahai over 6 years ago in reply to Siri

TI__Prodigy 150 points

Thank you Siri. I just don´t understand this part:

 /* Create packet with incrementing sequence number and random payload */
        packet[0] = (uint8_t)(seqNumber >> 8);
        packet[1] = (uint8_t)(seqNumber++);
        uint8_t i;
        for (i = 2; i < PAYLOAD_LENGTH; i++)
        {
            packet[i] = rand();
        }

Here I see the sequence number (00 xx) increasing and the payload. I don´t see the preamble and crc?

And if I want to send 4 packets with 250 bytes each, how big shoud be the interval between the packets? Speed is really important for the application.

Thanks in advance!

0 Siri over 6 years ago in reply to Azor_Ahai

TI__Guru* 81091 points

Preamble, sync and CRC is configured through the API:

RF_cmdPropRadioDivSetup.preamConf.nPreamBytes = 0x4,

RF_cmdPropRadioDivSetup.formatConf.nSwBits = 0x20,

RF_cmdPropTx.pktConf.bUseCrc = 0x1,

This is explained in the TRM

You can remove the delay and transmit a new packet as soon as a packet is sent, and you can also chain one TX command to the next. Command chaining is explained here:

http://dev.ti.com/tirex/content/simplelink_cc13x0_sdk_1_40_00_10/docs/proprietary-rf/proprietary-rf-users-guide/rf-core/conditional-execution-and-chaining.html?highlight=chaining

0 Azor_Ahai over 6 years ago in reply to Siri

TI__Prodigy 150 points

Thank you very much!

Sub-1 GHz

Sub-1 GHz forum

CCS/CC1350: CC1350: Packet interval & Payload length?