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Hi Russ,

Thanks for your reply,

I'll try to use the "transmit on CCA" feature of the CC1101.

The test I did before was like this:

First I use RF2 sending data to RF1 in 100ms interval, then open RF3 as well. The result is RF1 could only receive data from RF3. And even when RF3 was closed, RF1 still could not receive data from RF2.

Why did that happen?In my understanding, RF1 should receive the data from RF2 when RF3 is closed. However, RF2 seems dead in there although it was sending data all the time.

Any idea is welcome,

Thanks a lot!

Hi Jiang,

You are correct that it should be able to receive RF2 again after you stop RF3 from transmitting. There must be some other problem but it is hard to say what it might be without knowing more about your code. What code are you using? Is this using sample code from TI, or SimpliciTI, or your own code?

It could be that when RF3 starts transmitting, it causes RF2 to go into some state where it doesn't transmit any more. Does RF1 receive RF3 again after resetting RF3? Or do you have to reset RF1?

Russ

 

Hi Russ,

Thanks for your reply.

The most probability is that RF3 causes RF2 to go into some state where it doesn't transmit any more.

RF1 can receive RF3 properly when it sends data again. And it dose no need to reset RF1, as it is working properly all the time.

However, RF2 is not so lucky, it has to be reset if it want to be received or to receive data from others.

 

I use code written by myself, and configuration parameter is generated by SmartRF Studio.

Three RF modules almost use the same parameter. But there's a little difference.

 

Actually, configuration of RF1 is as following:

Address:0x01

Address check: yes, without broadcast address.

Working sate: RX in normal, and RXOFF_MODE and TXOFF_MODE stay in RX

 

 

 configuration of RF2 is as following:

Address:0x02

Address check: yes, with broadcast address.

Working sate: TX in normal, and  TXOFF_MODE stay in TX

So it can send data  all the time in theory.(sending address is 0x01)

 

The following is a general configuration used by my RF module.

 

/********************************************************************************************************/

// Chipcon

// Product = CC1100

// Chip version = F   (VERSION = 0x03)

// Crystal accuracy = 10 ppm

// X-tal frequency = 26 MHz

// RF output power = 0 dBm

// RX filterbandwidth = 232.142857 kHz

// Deviation = 32 kHz

// Datarate = 76.766968 kBaud

// Modulation = (0) 2-FSK

// Manchester enable = (0) Manchester disabled

// RF Frequency = 914.999969 MHz

// Channel spacing = 199.951172 kHz

// Channel number = 0

// Optimization = -

// Sync mode = (3) 30/32 sync word bits detected

// Format of RX/TX data = (0) Normal mode, use FIFOs for RX and TX

// CRC operation = (1) CRC calculation in TX and CRC check in RX enabled

// Forward Error Correction = (0) FEC disabled

// Length configuration = (1) Variable length packets, packet length configured by the first received byte after sync word.

// Packetlength = 64

// Preamble count = (2)  4 bytes

// Append status = 1

// Address check = (0) No address check

// FIFO autoflush = 0

// Device address = 0

// GDO0 signal selection = ( 7) Asserts when a packet has been received with OK CRC. De-asserts when the first byte is read from the RX FIFO

// GDO2 signal selection = (46) High impedance (3-state)

RF_SETTINGS  rfSettings = {

    0x08,   // FSCTRL1   Frequency synthesizer control.

    0x00,   // FSCTRL0   Frequency synthesizer control.

    0x23,   // FREQ2     Frequency control word, high byte.

    0x31,   // FREQ1     Frequency control word, middle byte.

    0x3B,   // FREQ0     Frequency control word, low byte.

    0x7B,   // MDMCFG4   Modem configuration.

    0x83,   // MDMCFG3   Modem configuration.

    0x03,   // MDMCFG2   Modem configuration.

    0x22,   // MDMCFG1   Modem configuration.

    0xF8,   // MDMCFG0   Modem configuration.

    0x00,   // CHANNR    Channel number.

    0x42,   // DEVIATN   Modem deviation setting (when FSK modulation is enabled).

    0xB6,   // FREND1    Front end RX configuration.

    0x10,   // FREND0    Front end TX configuration.

    0x18,   // MCSM0     Main Radio Control State Machine configuration.

    0x1D,   // FOCCFG    Frequency Offset Compensation Configuration.

    0x1C,   // BSCFG     Bit synchronization Configuration.

    0xC7,   // AGCCTRL2  AGC control.

    0x00,   // AGCCTRL1  AGC control.

    0xB2,   // AGCCTRL0  AGC control.

    0xEA,   // FSCAL3    Frequency synthesizer calibration.

    0x2A,   // FSCAL2    Frequency synthesizer calibration.

    0x00,   // FSCAL1    Frequency synthesizer calibration.

    0x1F,   // FSCAL0    Frequency synthesizer calibration.

    0x59,   // FSTEST    Frequency synthesizer calibration.

    0x81,   // TEST2     Various test settings.

    0x35,   // TEST1     Various test settings.

    0x09,   // TEST0     Various test settings.

    0x0E,   // FIFOTHR   RXFIFO and TXFIFO thresholds.

    0x2E,   // IOCFG2    GDO2 output pin configuration.

    0x07,   // IOCFG0D   GDO0 output pin configuration. Refer to SmartRF?Studio User Manual for detailed pseudo register explanation.

    0x04,   // PKTCTRL1  Packet automation control.

    0x05,   // PKTCTRL0  Packet automation control.

    0x00,   // ADDR      Device address.

    0x40    // PKTLEN    Packet length.

};

/**********************************************************************************************************************************/

Hi Jiang,

I can't see anything obviously wrong with your approach although I didn't check through all the details of your register settings. Some things you could try to narrow down the problem:

• Run your system with RF2 on the debugger so you can examine what is happening in the code when you start RF3 transmitting.
• Try to find out if RF2 is transmitting but with incorrect settings, or not transmitting at all - us a spectrum analyzer if you have one to see if it is transmitting anything out the antenna.

Russ

 

Hi Russ, I've figured out that RF2 is in TX_UNDERFLOW state when RF2 is dead, so I add state check mechanism to make it into TX state by sending the SFTX command. And it works ok now whenever using CCA or not. In my another test, which two RF are both in trans and receiv mode.That is TXOFF->RX, RXOFF->RX. I use an interrupt routine to receive RF data, and poll the uart port of MCU in the main function for the incoming data and transmit it through RF. They work just ok when the interval of sending data to uart is 100ms. Two RF can receive data from each other. However, when the interval is reduced to 10ms, the program seems abnormal, dead in there. So I give up the interrupt method, and move the routine to main function as well. Now they work ok, however may lost some RF data as expected. Is there any good way of transmitting a large amount of data with much higher speed between RF ends? And what speed can CC1101 support? Any idea is welcome, Thanks.

Yes, that would cause RF2 to stop transmitting. That's good you figured it out.

The CC1101 can operate up to 600kbps so you could speed it up quite a lot from the 76.8kbps that you are using. There is some overhead of course in each packet so you want to make your packet size as large as practical. These things are always a trade-off with radio performance - if you increase the data rate the receiver sensitivity gets worse (you can see this in the data sheet) - if you increase the packet size the probability of an error in the packet goes up. So you have to decide on how to trade those off.

Russ

 

hello sir,

i have two CC1101 and i trying to send data from one to other one...

i am writting the data and after i send the Tx strobe.

the second one is already in Rx mode.

the registers i set them from the TI programm.

i have to do anything else to work?

please help me.