CC1310: Wide-Band DSSS and FEC

Ali Awan75

Part Number: CC1310

Hi forum

I would like to operate CC1310 in wideband DSSS mode and FEC turned on @ 500 kbps...

I have setup my 2 boards as follows:

RF_Mode RF_prop =
{
.rfMode = RF_MODE_PROPRIETARY_SUB_1
.cpePatchFxn = &rf_patch_cpe_genfsk,
.mcePatchFxn = &rf_patch_mce_wb_dsss,
.rfePatchFxn = 0,
};

// Overrides for CMD_PROP_RADIO_DIV_SETUP
uint32_t pOverrides[] =
{
    MCE_RFE_OVERRIDE(1, 0, 0, 0, 4, 0), // MCE run from RAM, No RFE patch (PA ramping)
    //MCE_RFE_OVERRIDE(1, 0, 0, 1, 0, 0), // MCE and RFE run from patch, PA ramp patch applied
    HW32_ARRAY_OVERRIDE(0x6088,1),
    (uint32_t)0x0000001A,
    HW32_ARRAY_OVERRIDE(0x4038,1),
    (uint32_t)0x00000037,
    HW_REG_OVERRIDE(0x4020,0x7F00),
    HW_REG_OVERRIDE(0x4064,0x0040),
    (uint32_t)0x684A3,   // Synth: Set FREF = 4 MHz (24 MHz / 6)
    (uint32_t)0xC0040141,
    (uint32_t)0x0533B107,
    (uint32_t)0x0A480583,
    (uint32_t)0x7AB80603,
    (uint32_t)0x02010403,
    (uint32_t)0x00108463,
    (uint32_t)0x04B00243,
    ADI_REG_OVERRIDE(1,4,0x1F),
    ADI_HALFREG_OVERRIDE(1,7,0x4,0x4),
    HW_REG_OVERRIDE(0x6084,0x35F1),
    (uint32_t)0x00038883,
    (uint32_t)0x00FB88A3,
    HW_REG_OVERRIDE(0x6088,0x1F0E), // AGC reference level
    HW_REG_OVERRIDE(0x608C,0x3F13), //PA ramping
    // TX power override
    ADI_REG_OVERRIDE(0,12,0xF9),
    // Overrides for LRM
    HW_REG_OVERRIDE(0x52AC,0x0B03), //DSSS = 4, K=4
    HW_REG_OVERRIDE(0x5108,0x0048), //Correlator Threshold for Sync
    //HW_REG_OVERRIDE(0x50F4,0x5014),
    //HW_REG_OVERRIDE(0x50F8,0x0050),
    ADI_REG_OVERRIDE(1,0x12,0x22), //Enable RX_OUTQP to ATEST0 and RX_OUTIN to ATEST 1
    (uint32_t)0xFFFFFFFF,
};

// CMD_PROP_RADIO_DIV_SETUP
rfc_CMD_PROP_RADIO_DIV_SETUP_t RF_cmdPropRadioDivSetup =
{
    .commandNo = 0x3807,
    .status = 0x0000,
    .pNextOp = 0, // INSERT APPLICABLE POINTER: (uint8_t*)&xxx
    .startTime = 0x00000000,
    .startTrigger.triggerType = 0x0,
    .startTrigger.bEnaCmd = 0x0,
    .startTrigger.triggerNo = 0x0,
    .startTrigger.pastTrig = 0x0,
    .condition.rule = 0x1,
    .condition.nSkip = 0x0,
    .modulation.modType = 0x0,          //Changed for LRM mode
    .modulation.deviation = 0x2bc,      //0x2bc, 175KHz deviation (250*100)
    .symbolRate.preScale = 0xf,         //0xf, Prescalar value of 15
    .symbolRate.rateWord = 0x50000,     //0x50000, 500kbps with prescalar of 15.
    .rxBw = 0x2F,                       //1410KHz bandwidth
    .preamConf.nPreamBytes = 0x4,
    .preamConf.preamMode = 0x0,
    .formatConf.nSwBits = 0x20,         //32 bit Sync word
    .formatConf.bBitReversal = 0x0,
    .formatConf.bMsbFirst = 0x0,        //LSB transmitted first for LRM mode
    .formatConf.fecMode = 0x0,          //Uncoded
    .formatConf.whitenMode = 0x0,
    .config.frontEndMode = 0x0,         //Differential
    .config.biasMode = 0x1,             //External Bias
    .config.bNoFsPowerUp = 0x0,
    .txPower = 0xa73f,
    .pRegOverride = pOverrides,
    .centerFreq = 915,
    //.intFreq = 0x8000,                  //TX IF default, 1MHz IF for RX
    .intFreq = 0x0064,                  //TX IF default, 1MHz IF for RX
    .loDivider = 0x05,
};

// CMD_FS
rfc_CMD_FS_t RF_cmdFs =
{
    .commandNo = 0x0803,
    .status = 0x0000,
    .pNextOp = 0, // INSERT APPLICABLE POINTER: (uint8_t*)&xxx
    .startTime = 0x00000000,
    .startTrigger.triggerType = 0x0,
    .startTrigger.bEnaCmd = 0x0,
    .startTrigger.triggerNo = 0x0,
    .startTrigger.pastTrig = 0x0,
    .condition.rule = 0x1,
    .condition.nSkip = 0x0,
    .frequency = 915,             //915MHz frequency
    .fractFreq = 0x0000,
    .synthConf.bTxMode = 0x0,
    .synthConf.refFreq = 0x0,
    .__dummy0 = 0x00,
    .__dummy1 = 0x00,
    .__dummy2 = 0x00,
    .__dummy3 = 0x0000,
};

// CMD_PROP_TX
rfc_CMD_PROP_TX_t RF_cmdPropTx =
{
    .commandNo = 0x3801,
    .status = 0x0000,
    .pNextOp = 0, // INSERT APPLICABLE POINTER: (uint8_t*)&xxx
    .startTime = 0x00000000,
    .startTrigger.triggerType = 0x0,
    .startTrigger.bEnaCmd = 0x0,
    .startTrigger.triggerNo = 0x0,
    .startTrigger.pastTrig = 0x0,
    .condition.rule = 0x1,
    .condition.nSkip = 0x0,
    .pktConf.bFsOff = 0x0,
    .pktConf.bUseCrc = 0x1,
    .pktConf.bVarLen = 0x1,
    .pktLen = 0x1e, // SET APPLICATION PAYLOAD LENGTH
    .syncWord = 0x333C3C33,
    .pPkt = 0, // INSERT APPLICABLE POINTER: (uint8_t*)&xxx
};

// CMD_PROP_RX
rfc_CMD_PROP_RX_t RF_cmdPropRx =
{
    .commandNo = 0x3802,
    .status = 0x0000,
    .pNextOp = 0, // INSERT APPLICABLE POINTER: (uint8_t*)&xxx
    .startTime = 0x00000000,
    .startTrigger.triggerType = 0x0,
    .startTrigger.bEnaCmd = 0x0,
    .startTrigger.triggerNo = 0x0,
    .startTrigger.pastTrig = 0x0,
    .condition.rule = 0x1,
    .condition.nSkip = 0x0,
    .pktConf.bFsOff = 0x0,
    .pktConf.bRepeatOk = 0x0,
    .pktConf.bRepeatNok = 0x0,
    .pktConf.bUseCrc = 0x1,
    .pktConf.bVarLen = 0x1,
    .pktConf.bChkAddress = 0x0,
    .pktConf.endType = 0x0,
    .pktConf.filterOp = 0x0,
    .rxConf.bAutoFlushIgnored = 0x1,
    .rxConf.bAutoFlushCrcErr = 0x1,
    .rxConf.bIncludeHdr = 0x1,
    .rxConf.bIncludeCrc = 0x0,
    .rxConf.bAppendRssi = 0x1,
    .rxConf.bAppendTimestamp = 0x0,
    .rxConf.bAppendStatus = 0x1,
    .syncWord = 0x333C3C33,
    .maxPktLen = 100, // MAKE SURE DATA ENTRY IS LARGE ENOUGH
    .address0 = 0xaa,
    .address1 = 0xbb,
    .endTrigger.triggerType = 0x1,
    .endTrigger.bEnaCmd = 0x0,
    .endTrigger.triggerNo = 0x0,
    .endTrigger.pastTrig = 0x0,
    .endTime = 0x00000000,
    .pQueue = 0, // INSERT APPLICABLE POINTER: (dataQueue_t*)&xxx
    .pOutput = 0, // INSERT APPLICABLE POINTER: (uint8_t*)&xxx
};

I now want to change the DSSS settings to SF=8 and Turn the FEC to on,

as you can see in my settings that right now I have SF=4 and FEC=off (uncoded)

I want to take advange to FEC and DSSS=8 at the same time

pleaes guide me

Best Regards

Ali

over 7 years ago

0 FI over 7 years ago

TI__Mastermind 21240 points

Hi Ali,

For DSSS = 8, please change the following override:

HW_REG_OVERRIDE(0x52AC,0x0B03), //DSSS = 4, K=4

HW_REG_OVERRIDE(0x52AC,0x0F33), //DSSS =8, K=4

also change rxBw = 0x2C for better sensitivity.

0 Ali Awan75 over 7 years ago in reply to FI

Expert 1740 points

Thankyou for your reply!
I would like to know how to enable fec ?
.formatConf.fecMode = 0x0, //Uncoded
Also what does K=4 imply?

0 TA12012 over 7 years ago in reply to Ali Awan75

TI__Mastermind 36395 points

Ali,

FEC is enabled by default, K=4 is the constraint length of the constitutional encoder.

Regards,
/TA

0 Ali Awan75 over 7 years ago in reply to TA12012

Expert 1740 points

I see but in case of LRM ...constraint length was k=7 when i used it...also i would enter .formatConf.fecMode = 0x8 in case of LRM,
I am very satisfied with indoor performance of LRM,i would like to get the same from wb dsss mode
Besides is it a constitutional encoder or convolution encoder?

0 FI over 7 years ago in reply to Ali Awan75

TI__Mastermind 21240 points

Hi Ali,
The convolutional encoder's constraint length is 4 in WB-DSSS case where as in LRM it is 7. The .formatConf.fecMode field in these cases works in conjunction with specific MCE patches. In case for WB-DSSS it should be set to 0x0.

In case for LRM where the data rates are lower, you will see better sensitivity performances where as in WB-DSSS case, where data rates are relatively higher, the sensitivity performance will be lower w.r.t LRM mode. In WB-DSSS case where DSSS = 8, you will see around -109dBm sensitivity. In case for DSSS = 1, you will observe around -104dBm.

What kind of RF performance are you looking for in your application?

0 bob frankel over 7 years ago in reply to FI

Expert 2460 points

just to verify, is it truly possible to set DSSS = 8, K = 4 for WB-DSSS???? my understanding had always been that the spreading factor was fixed at 4....

if this is indeed the case, would the effective data rate now be 31.25 kbps???? and would the transmitter still meet the FCC 500 kHz occupied bandwith requirement???

0 Ali Awan75 over 7 years ago in reply to FI

Expert 1740 points

I am looking for a following settings to achieve maximum sensitivity with data rate set @ 500kbps...i ve wb dsss patch applied with DSSS=4 and K=4...what sensitivity should i expect?

0 Ali Awan75 over 7 years ago in reply to FI

Expert 1740 points

I know that rx filter bandwidth has an inverse relationship with sensitivity since noise floor increases...how does DSSS=8 improve sensitivity as compared to DSSS=1?

0 FI over 7 years ago in reply to Ali Awan75

TI__Mastermind 21240 points

The improvement in sensitivity is due to the coding gain provided by the FEC block of the convolutional coder. With DSSS = 8 the effective data rate is reduced and more bits are then used for error correction hence improving the sensitivity.

0 Ali Awan75 over 7 years ago in reply to FI

Expert 1740 points

Ok thankyou but what sensitivity should i expect at my settings of 500 kbps and rx filter bandwidth of 622?

0 FI over 7 years ago in reply to Ali Awan75

TI__Mastermind 21240 points

In WB-DSSS application sensitivity depends on the DSSS setting. For DSSS = 8 you should see close to -109dBm.
Rx BW will remain the same for all DSSS cases since over the air datarate is always 500kbps.

0 TA12012 over 7 years ago in reply to FI

TI__Mastermind 36395 points

Ali,

Just confirming your question, the FEC is always on in the WBDSSS patch. Even when the FEC=0 is set, please leave FEC=0 as anthing else is not defined.

Regards,
/TA

0 Ali Awan75 over 7 years ago in reply to TA12012

Expert 1740 points

Ok thankyou..i will pick up some attenuators and verify the sensitivity now

0 Ali Awan75 over 7 years ago in reply to FI

Expert 1740 points

Throughtput for DSSS=4,K=4 would be 62.5kbps?

And if i turn off the DSSS factor...can i get 250kbps throughput?

What is the settings override?

0 FI over 7 years ago in reply to Ali Awan75

TI__Mastermind 21240 points

Following are the overrides.
HW_REG_OVERRIDE(0x52AC,0xB03),
//0xB03 for DSSS = 4; 0x0800 for DSSS = 1; 0x0900 for DSSS = 2; 0x0F33 for DSSS = 8

0 Ali Awan75 over 7 years ago in reply to FI

Expert 1740 points

Thank you
And what throughput should i expect at each setting?

0 FI over 7 years ago in reply to Ali Awan75

TI__Mastermind 21240 points

The following relationship is applicable:
DataRate = symbolRate/2/DSSS.
e.g for DSSS = 4
Datarate = 500/2/4 = 62.5kbps

0 Ali Awan75 over 7 years ago in reply to FI

Expert 1740 points

Thank you for the reply!

I see i am having a problem trying to quickly change rf frequency with easlink api..i am using wb dsss patch and settings are same as shared in my original post...when i change smart rf settings to predefined gfsk mode...i am able to quickly change frequency but not in wb dsss mode...why is the PLL processing slowly?

0 Ali Awan75 over 7 years ago in reply to FI

Expert 1740 points

Besides when will we be able to set rf baud to greater than 500 kbps and dsss=8 to achieve greater throughput?

0 FI over 7 years ago in reply to Ali Awan75

TI__Mastermind 21240 points

So far there is no plan to characterize baudrate greater than 500kbps in in WB-DSSS mode.
If you want higher data rate e.g 1.5Mbps please see this e2e.ti.com/.../2363574

0 Ali Awan75 over 7 years ago in reply to FI

Expert 1740 points

Hi FL

I dont want higher data rate in normal mode.i want throughput of 250 kbps with DSSS=4 or DSSS=8 i-e rf symbol rate of 2mbps or 4mbs in wb dsss mode...is that possible in current rtos release or IC rev?

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CC1310: Wide-Band DSSS and FEC