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CC2500: Maximum practically achievable data rate

venugopal kapre
Intellectual 835 points

Part Number: CC2500

Hello,

I am using CC2500 with PIFA antenna & matching network provided by TI. The chip works fine with lower data rates < 19.2Kbps. As I increase the data rate, the chip starts missing the packet & above 40 Kbps, it stops reception.

I am using 2-FSK modulation scheme & Bandwidth of 200 KHz (4*data rate).

TI datasheet promises 500 Kbps data rate.

I want data rate of at least 100 Kbps.

Please help.

Thanks

  • 0
    TI__Guru** 106705 points
    Hi Venugopal,

    For proper operation you must ensure that you use the appropriate radio register settings for each datarate and modulation. Refer to the datasheet and the settings in SmartRF Studio for details.

    Cheers,
    Fredrik
  • 0 in reply to Fredrik K
    Intellectual 835 points

    Hi Fredrik,

    Following are my register settings.

    Modulation = 2 - FSK, Deviation = 38.02KHz (for all below cases)

    MDMCFG2 = 0x03, DEVIAT = 0x44.

    Case 1: Data Rate = 4.8Kbps, BW = 203.125kHz

    MDMCFG3 = 0x83, MDMCFG4 = 0x87

    Communication is reliable.

    Case 2: Data Rate = 19.2 Kbps, BW = 203.125 kHz

    MDMCFG3 = 0x83, MDMCFG4 = 0x89

    Communication is reliable.

    Case 3: Data Rate = 40Kbps, BW = 203.125kHz

    MDMCFG3 = 0x33, MDMCFG4 = 0x8A

    Communication is reliable.

    Case 4: Data Rate = 90 Kbps, BW = 541.666 kHz

    MDMCFG3 = 0xC6, MDMCFG4 = 0x2B

    Communication is not reliable.

    Case 5: Data Rate = 115Kbps, BW = 650kHz

    MDMCFG3 = 0x22, MDMCFG4 = 0x1C

    Communication is not reliable.

    Please have a look at it & let me know.

    Thanks

    Venu

     

  • 0 in reply to venugopal kapre
    TI__Mastermind 39860 points
    Not sure how you derive at the settings you have used for your testing, but assuming you use 2.4 kbps , BW = 203 kHz as starting point and simply change the data rate and BW for the different test cases you will get sub-optimum (or even non-working) settings at higher data rates.

    For cases 4 and 5 make sure you set FSCTRL1, AGCCTRL2, AGCCTRL1, AGCCTRL0, and FREND1 to the values you get when you select 250 kbps, BW = 541 kHz in SmartRF Studio (0x0A, 0xC7, 0x0, 0xB0, and 0xB6 respectively).
  • 0 in reply to Sverre
    Intellectual 835 points

    The issue is resolved. In stead of 2-FSK modulation, I used MSK with default setting from Smart RF studio. There seems to be problem with 2-FSK modulation scheme at higher data rate.

    Can you elaborate the details of filter (to which we specify BW through register setting) used before PA ?

    Thanks

    Venu