CC1101: CCA and CS not working in CC1101

Hi Harsh,

I have assigned this thread to an expert. They will get back to you with some feedback. 

Regards,
Siddanth

Please provide info regarding what settings from SmartRF Studio you are using, so that I do not need to go through every register and field to figure out your configuration.

Also, what do you mean by “not working”? How is it failing?

I see that you use CCA_MODE = 2 (unless currently receiving a packet). This means that your device will enter TX even if another device has started to send for example preamble. If this is the case, more than one device will send at the same time, and none of the packets will be received.

You should also avoid using off modes (at least when you are testing). This way it is much easier to figure out what state the device is in, and what is going on.

I assume that you meant that you strobe SRX before TX, and not STX? If, not, it is no wonder CCA is not working, as the device must be in RX to be able to figure out if the channel is available or not.

Also, why are you using different settings in RX and TX?

A simple test you can do is to use one of the default settings in SmartRF Studio and then just enable CCA (Set CCA mode = 1 or 3). Write a packet to the TX FIFO, Strobe SRX and then STX.

Use another device to be the jammer. You can then see that if a jammer is present, strobing STX after SRX will cause the device to stay in RX, while it will go to TX and then IDLE, if the channel is clear.

If you use CCA mode = 2 and do the same exercise, and have a jammer just sending modulated data, the packet will be send even if the jammer is really strong, since the radio has not found any sync word.

Siri said:

Please provide info regarding what settings from SmartRF Studio you are using, so that I do not need to go through every register and field to figure out your configuration.

Here is setting from SmartRF Studio.

Siri said:

Also, what do you mean by “not working”? How is it failing?

We have two receiver and two transmitter as same place. Both are working individually but at same time its not working. Both receiver are on same channel and but different address. We want to work both at same time but its not working.

Siri said:

I see that you use CCA_MODE = 2 (unless currently receiving a packet). This means that your device will enter TX even if another device has started to send for example preamble. If this is the case, more than one device will send at the same time, and none of the packets will be received.

Yes i have use CCA_MODE = 2. Than which mode should i use for that? I have also check with CCA_MODE = 1 and CCA_MODE = 3 but not working.

Siri said:

You should also avoid using off modes (at least when you are testing). This way it is much easier to figure out what state the device is in, and what is going on.

Now i'll check with IDEL Mode.

Siri said:

I assume that you meant that you strobe SRX before TX, and not STX? If, not, it is no wonder CCA is not working, as the device must be in RX to be able to figure out if the channel is available or not.

I have corrected this but still its not working.

Siri said:

Also, why are you using different settings in RX and TX?

For RX i used Carrier sense and for TX i used CCA.

Do you have any flow chart so that we can follow that chart for CCA to work.

Best regards

Harsh

I understand that your application is not working the way you want it to, but this does not mean that CCA is not working.

The first thing you need to do is to test the CCA feature separately to make sure that it works.

You should then use recommended settings from SmartRF Studio based on your RF parameters, without doing a lot of packet handling changes and other changes (you are modifying WOR register, address filtering, off modes etc.) I also noted that you are making changes to registers that are stated that you need to use settings from SmartRF Studio (for example MDMCFG1). You should not do that.

From SmartRF Studio you get the following settings for the RF parameters that you have chosen:

// Address Config = No address check 
// Base Frequency = 314.999664 
// CRC Autoflush = false 
// CRC Enable = true 
// Carrier Frequency = 314.999664 
// Channel Number = 0 
// Channel Spacing = 338.012695 
// Data Format = Normal mode 
// Data Rate = 9.9926 
// Deviation = 19.042969 
// Device Address = 0 
// Manchester Enable = false 
// Modulated = true 
// Modulation Format = GFSK 
// PA Ramping = true 
// Packet Length = 255 
// Packet Length Mode = Variable packet length mode. Packet length configured by the first byte after sync word 
// Preamble Count = 4 
// RX Filter BW = 58.035714 
// Sync Word Qualifier Mode = 30/32 sync word bits detected 
// TX Power = 0 
// Whitening = true 
// PA table 
#define PA_TABLE {0x00,0x12,0x0d,0x33,0x69,0x63,0x52,0x51}

static const registerSetting_t preferredSettings[]= 
{
    {CC1101_IOCFG0, 0x06},
    {CC1101_FIFOTHR, 0x47},
    {CC1101_FSCTRL1, 0x06},
    {CC1101_FREQ2, 0x0C},
    {CC1101_FREQ1, 0x1D},
    {CC1101_FREQ0, 0x89},
    {CC1101_MDMCFG4, 0xF8},
    {CC1101_MDMCFG3, 0x93},
    {CC1101_MDMCFG2, 0x13},
    {CC1101_MDMCFG1, 0x23},
    {CC1101_MDMCFG0, 0xAA},
    {CC1101_DEVIATN, 0x34},
    {CC1101_MCSM0, 0x18},
    {CC1101_FOCCFG, 0x16},
    {CC1101_AGCCTRL2, 0x43},
    {CC1101_WORCTRL, 0xFB},
    {CC1101_FREND0, 0x17},
    {CC1101_FSCAL3, 0xE9},
    {CC1101_FSCAL2, 0x2A},
    {CC1101_FSCAL1, 0x00},
    {CC1101_FSCAL0, 0x1F},
    {CC1101_TEST2, 0x81},
    {CC1101_TEST1, 0x35},
};

To test CCA you do not have to do anything to these settings.

• Make a small test program where you do the following:
• Init MCU
• Init radio with the settings above
• Write a packet to the TX FIFO
• Strobe SRX to enter RX Mode (you can here poll marcstate to make sure that the radio has had time to enter RX before you strobe STX)
• Strobe STX to transmit the packet

If the channel is available the packet will be sent and the radio will enter IDLE state

If the channel is BUSY, the radio will remain in RX.

The test above is what you need to start testing, to verify that your CS Threshold is set correctly.

Once you have verified that this works (it can even be tested with SmartRF Studio as I explained in the first post), you need to start debug your application to figure out why it does not work.

To debug this it is useful to output the LNA and PA signals to some GDO pins to figure out when your devices are in RX and TX, to better understand what goes wrong.

Siri

Thank you very much for update.

Siri said:

To test CCA you do not have to do anything to these settings.

• Make a small test program where you do the following:
• Init MCU
• Init radio with the settings above
• Write a packet to the TX FIFO
• Strobe SRX to enter RX Mode (you can here poll marcstate to make sure that the radio has had time to enter RX before you strobe STX)
• Strobe STX to transmit the packet

If the channel is available the packet will be sent and the radio will enter IDLE state

If the channel is BUSY, the radio will remain in RX.

The test above is what you need to start testing, to verify that your CS Threshold is set correctly.

Once you have verified that this works (it can even be tested with SmartRF Studio as I explained in the first post), you need to start debug your application to figure out why it does not work.

I'll check with Smart RF Studio (I'll connect CC debugger to CC1101) with above setting. After that I'll post an update.

Siri said:

To debug this it is useful to output the LNA and PA signals to some GDO pins to figure out when your devices are in RX and TX, to better understand what goes wrong.

For this i use GDO_CFG = 0x09(Clear channel assessment) or 0x0E(Carrier sense)

Harsh