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TDC1000-C2000EVM: TDC1000-C2000EVM and its GUI (40kHz transducer)

Alessandro Blason
Prodigy 30 points
Part Number: TDC1000-C2000EVM
Other Parts Discussed in Thread: TDC1000

Hi,

I started experimenting with this board and the software TDC1000-C2000EVM GUI. Currently I use 40Khz transducer so my intention is to inject 80Khz on CLKIN with TX_FREQ_DIV set to divide by 2. 

In the GUI software (SETUP folder) I select TDC_CLK_SOURCE_SELECT = EXT CLK. The problem is that the field TDC_CLK_FREQ it seems accept only a range from 1MHz to 16Mhz.

Which value I must enter in this field?

Thanks in advance

Alex

  • 0
    TI__Genius 11015 points
    Alessandro,

    I have received your question & I will respond within the next couple of days,
  • 0
    TI__Genius 11015 points
    Alex,

    The CLKIN for the TDC1000 has only a max value of 16MHz. Also you can only use an external clock in the range 1MHz to 16Mhz.
    Change eternal clock to 1.28Mhz and choose the TX_FREQ_DIV to 32 to use the 40Khz transducer.
  • 0 in reply to Bharat Aravamudhan
    Prodigy 30 points

    Hi Bharat,

    but I still don't understand why the lower limit is 1MHz since the TDC1000 datasheet say at page 4

    6.3 Recommended Operating Conditions

    ƒCLKIN Operating frequency 0.06 16 MHz

    so the lower limt it should be 60KHz according to the datasheet and not 1MHz.

    Moreover i do not understand why the software must know the external frequency since TDC1000 doest need to know the value of the CLKIN frequency

    Thanks

    Alex

  • 0 in reply to Alessandro Blason
    TI__Genius 11015 points
    Alessandro,

    See, the clock divider allows the TDC1000 to divide the clock source that is connected to the CLKIN pin down to the resonant frequency (ƒR)
    of the transducer used. The clock divider allows division factors in powers of 2. The division factor of the clock divider can be programmed with the TX_FREQ_DIV field in the CONFIG_0 register. Also note the GUI & device should know the external clock frequency for us to match it with the resonant frequency of the transducer.

    Also the EVM & GUI is configured mostly for detecting level & concentration measurement of liquids/gas and we typically use higher freq in the range of few MHz for such applications and hence it is limited from 1Mhz.
  • 0 in reply to Bharat Aravamudhan
    Prodigy 30 points

    Thanks Bharat,

    I understand the purpose of TX_FREQ_DIV in CONFIG_0 register....but you say "Also note the GUI & device should know the external clock frequency" so can you help me to find where, in the datashet, it's explained how to tell to TDC1000 the clock frequency applied to CLKIN? Is there a dedicated register? 

    Thanks
    Alessandro

  • 0 in reply to Alessandro Blason
    TI__Genius 11015 points
    Alessandro,

    We need to match the external clock frequency with the resonant frequency of the transducer. When we use the GUI with the EVM in such case we mention the external clock frequency in the GUI for it to match the resonant frequency of the transducer.

    Also note the TX_FREQ_DIV register in the device TDC1000 helps to divide the CLKIN pin frequency to the resonant frequency of the transducer in use.