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CC1200: CC1200(863 MHz to 870 MHz) unable to send on Channels number greater than 27 weired issue?

Hassaan Shah
Intellectual 340 points
Part Number: CC1200
Other Parts Discussed in Thread: CC1101, CC1100

Dear All,

During our product development we are facing a weird issue CC1200(863 MHz to 870 MHz) is unable to send on Channels number greater than 27 but Reception is working fine. Why this strange issue.

Our CC1200 Settings:

    {CC120X_IOCFG2,            0x18},
    {CC120X_IOCFG0,            0x06},
    {CC120X_SYNC3,             0xd3},
    {CC120X_SYNC2,             0x91},
    {CC120X_SYNC1,             0xD3},
    {CC120X_SYNC0,             0x91},
    {CC120X_SYNC_CFG1,         0xA8},
    {CC120X_SYNC_CFG0,         0x03},
    {CC120X_DEVIATION_M,       0x06},
    {CC120X_MODCFG_DEV_E,      0x0A},
    {CC120X_DCFILT_CFG,        0x5D},
    {CC120X_PREAMBLE_CFG1,     0x1A},
    {CC120X_PREAMBLE_CFG0,     0x8A},
    {CC120X_IQIC,              0xcb},
    {CC120X_CHAN_BW,           0x84},
    {CC120X_MDMCFG1,           0x40},
    {CC120X_MDMCFG0,           0x05},
    {CC120X_SYMBOL_RATE2,      0x8A},
    {CC120X_SYMBOL_RATE1,      0x3E},
    {CC120X_SYMBOL_RATE0,      0x65},
    {CC120X_AGC_REF,           0x27},
    {CC120X_AGC_CS_THR,        0x01},
    {CC120X_AGC_CFG1,          0x51},
    {CC120X_AGC_CFG0,          0x8b},
    {CC120X_FIFO_CFG,          0x00},
    {CC120X_FS_CFG,            0x12},
    {CC120X_PKT_CFG2,          0x00},
    {CC120X_PKT_CFG1,          0x41},
    {CC120X_PKT_CFG0,          0x20},
    {CC120X_PA_CFG1,           0x7F},
    {CC120X_PA_CFG0,           0x52},
    {CC120X_PKT_LEN,           0xFE},
    {CC120X_IF_MIX_CFG,        0x18},
    {CC120X_FREQOFF_CFG,       0x2e},
    {CC120X_TOC_CFG,           0x0b},
    {CC120X_MDMCFG2,           0x00},
    {CC120X_FREQ2,             0x56},
    {CC120X_FREQ1,             0x4F},
    {CC120X_FREQ0,             0x5C},
    {CC120X_IF_ADC1,           0xEE},
    {CC120X_IF_ADC0,           0x10},
    {CC120X_FS_DIG1,           0x07},
    {CC120X_FS_DIG0,           0xaf},
    {CC120X_FS_CAL1,           0x40},
    {CC120X_FS_CAL0,           0x0E},
    {CC120X_FS_DIVTWO,         0x03},
    {CC120X_FS_DSM0,           0x33},
    {CC120X_FS_DVC0,           0x17},
    {CC120X_FS_PFD,            0x00},
    {CC120X_FS_PRE,            0x6E},
    {CC120X_FS_REG_DIV_CML,    0x1C},
    {CC120X_FS_SPARE,          0xAC},
    {CC120X_FS_VCO0,           0xB5},
    {CC120X_IFAMP,             0x0D},
    {CC120X_XOSC5,             0x0E},
    {CC120X_XOSC1,             0x03},
    {CC120X_DEV_ADDR,          0x00},
    {CC120X_RFEND_CFG1,        0x3e},

Kindly guide us. Thank you

Regards,

MHS

  • 0
    TI__Guru**** 317180 points
    - According to which standard are you numbering the channels? Reading the post it's not clear exactly which frequency this is.
    - How do you know that the receiver works (when you are not able to send with the board) Based on the sync word, did you test with CC1101 as TX when testing the receiver?
    - Have you measured the output in TX with a spectrum to see if you send something on some frequencies?
    - Could you describe the system some? What do you do when you try to send on the channels that doesn't work?
  • 0 in reply to TER
    Intellectual 340 points
    [1] we are using 866 MHz band with starting channel 0 = 863 MHz base frequency
    [2] We are using CC1101 as Tx device and CC1200 as Rx, but when we make CC1200 as Tx our CC1101 is not able to receive on Channels greater than 27
    [3] Yes we have spectrum analyzer and it shows some activity on channels greater than 27 but CC1101 Rx is not able to receive somehow. Channels 0 to 26 works fine both as Tx and Rx on every CC1101 & CC1200
    [4] We are using the same firmware for channels 0 to 26 and for channels 27 to 56
  • 0 in reply to Hassaan Shah
    TI__Guru**** 317180 points
    ...and how wide is the channel?

    I assume that you do exactly the same when you try to use channel 0 as channel 56? It should be no difference in how the chip behave @863 MHz and @870 MHz.

    Are you able to use SmartRF Studio to control the CC1200 board via a CCdebugger?
  • 0 in reply to TER
    Intellectual 340 points

    Hi,
    We have observed that with the increase of channel number like 10 or above the LQI value start increasing from 42 , and finally at channel 27(LQI is 127) or above the CC1101 RX is enable to receive any signal from CC1200 TX

  • 0 in reply to Hassaan Shah
    TI__Guru**** 317180 points
    That does not give me any new/ useful information. Please answer the question I asked in my previous post.
  • 0 in reply to TER
    Intellectual 340 points

    Hi TER,

    Symbol Rate/ Bit Rate = 32.0358 kbps

    Rx Filter Bandwidth = 101.562500 KHz

    Deviation = 9.54 KHz

    Band used = 863 MHz to 870 MHz

    And we don't have access to CC1200 866 MHz dev boards. 

    regards,

    MHS

  • 0 in reply to Hassaan Shah
    TI__Guru**** 317180 points
    - Why the low modulation index?
    - I haven't done any calculations but the RX BW looks high, do you have a high ppm xtal?

    - My question was if you were able to control the CC1200 on your board via a CCDebugger (this will require that you can access the SPI interface without the MCU driving the lines) . Testing with SmartRF Studio could rule out any software issues.

    - Have you tried to set the freq word, do a SCAL and STX on the lowest and the highest channel?
    - You wrote that you see some activity on the spectrum if you try with a channel higher than 27. Have you compared the spectrum plot when you send at a channel where you are able to receive and a channel where you are not able to receive?
  • 0 in reply to TER
    Intellectual 340 points

    [1] Same Rx BW is being used on CC1101 side also and no issue on it. For CC1200 PPM crystal is 40 MHz default
    [2] I haven't manually set Freq Reg. But I will try it manually
    [3] Spectrum Analyzer shows activity on all channels we are using 0 to 56. But as in my previous reply. We observed that our RSSI is valid but with increasing channel number LQI increases to a point 127 value. where CC1101 Rx is unable to receive.

    [4] We are using CC1200 with 915 MHz and up till now no issue is observed on it.

    [5] Screen shots are also attached.

    Normal communication at channel 17 (CC1101 Rx) Side

    Issue Started Channel (19) (CC1101 Rx) Side

  • 0 in reply to Hassaan Shah
    TI__Guru**** 317180 points
    I'm awaiting the answer for:
    - Have you tried to set the freq word, do a SCAL and STX on the lowest and the highest channel?
    - You wrote that you see some activity on the spectrum if you try with a channel higher than 27. Have you compared the spectrum plot when you send at a channel where you are able to receive and a channel where you are not able to receive?

    Since i don't know what type of software you are running the logs you attached does not contain any useful information.
  • 0 in reply to TER
    TI__Guru**** 317180 points
    Any more feedback on this?
  • 0 in reply to TER
    Intellectual 340 points

    Dear All,

                  we solved the issue by changing the Rx Filter bandwidth and Deviation as per our project.

                   Rx filter bandwidth for our scenario was changed 104 kHz to 205 KHz

                   Deviation for our scenario was changed 10 KHz to 24 KHz

    and everything started working properly b/w CC1100 & CC1200 and vice versa.

    regards,

    MHS