TDC7201: Estimate for measurement 5000 times per second

Tao_2199

Genius 5770 points

Part Number: TDC7201

Hello,

Regarding to the application with TDC7201, my customer have a question.

They will design with the following conditions.

･TOF distance : 2000cm(20m)

･TOF durations(start-stop) : 133ns (2000cm+2000cm)/(30cm/ns)= 133.3ns

･Measurement Mode : Mode 1(12 ns to 2000 ns) or Combined mode (0.25 ns to 8 ms)

･TDC7201 fCALIB_CLK : 8MHz

･SPI fSCLK : 20MHz (Host: MPS430)

They will design the performing distance measurement 5000 times per second with above conditions.

Are their designs valid? Is there any problem as total system?

Regards,

Tao2199

over 8 years ago

0 Scott Cummins over 8 years ago

TI__Mastermind 31655 points

Hello,

To measure at 5kHz, the entire process must take less than 200us. The majority of the time will be in reading the 24 bit CLK COUNT, TIME, and 2 CALIBRATION registers. Overall, reading those 4 registers will take about 5us with a 20Mhz SPI clock, with an additional 1us or so for the calibration cycles. Rounding the TOF up to 1us, that makes 7us total for the measurement and read cycle. This is well within the limits for a 5kHz measurement cycle.

Regards,

0 Kz777 over 8 years ago in reply to Scott Cummins

TI__Expert 7895 points

Hi Scott , I think MSP430 or MSP432 is not able to realize 20MHz SPI clock . What kind of MCU are you expect for this 20Mhz SPI operation ?
Regards,
Kz777

0 Scott Cummins over 8 years ago in reply to Kz777

TI__Mastermind 31655 points

The MSP430 on the TDC1000-TDC7200EVM is this one: www.ti.com/.../msp430f5529.pdf

The SPI clock frequency can run up to the Fsystem, which can in turn be run at 20Mhz according to the datasheet.

Regards,

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TDC7201: Estimate for measurement 5000 times per second