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TDC7201: Several questions about application.

Ryan Lee TW
Intellectual 506 points
Part Number: TDC7201
Other Parts Discussed in Thread: TDC1000, TDC7200

Hi Expert,

My customer want to use TDC7201 in LiDAR application, and there are several questions about that.

Q1. What are the exactly application about 2nd STOP to 5th STOP, as we know TOF can be simulated by the time between START to 1st STOP. 

Q2.  Is there a command flow chart about TDC7201 if customer do not want to use MSP430 to control?

Q3. If the "Trigger " pin is not connected due to a special design problem, is there any other way to confirm the IC status?

Q4. Does it provide automatic switching between far/near mode? If not, is there any suggestion for sample code to achieve this application?

Q5. If customer not use MSP430 to control TDC, but use other MCUs to trigger the TDC7201 EVM, find that a voltage drop occured for the start_ex1/2.(3V -> 1V)

So the following problems are:

Whether the following signal pins of TDC7201 have specified voltage/time/drive current?

1- TRIG1/2

2- Start_ext1/2

3- Stop_ext1/2

Thanks a lot.

  • 0
    TI__Mastermind 19640 points

    Hello Ryan,

    Thanks for the posting to the PS forum!

    1. The TDC7201 has the option to time up to 5 STOP signals from one START. This function is available on the device because is meant to also work with TDC1000 which is an ultrasonic AFE that can generate multiple stop signals for one measurement. While it could have a use case for a LiDAR application, this isnt something I have come across in the past.

    2. Not sure if I understand this question, could you clarify what you mean by command flow chart? Do you mean like a series of steps on how a measurement is performed?

    3. The TRIGG pin generates an output when it is time to start a new measurement, but before the TRIGG pin is generated after you start a new measurement by writing a 1 to the CONFIG1 register. So technically you know when a measurement can be started. The signal that does need to be collected is the INTB pin which lets you know when a measurement has been completed. If you attempt to read the results register during a measurement this causes the measurement to be aborted.

    4. The TDC7200 does not provide automatic switching for far and near mode, and we do not have any sample code to achieve this.

    5. If the voltage is dropped from 3V to 1V, then it is possible that a measurement will not be started because the device will not recognize it as a high input.

    There are certain time requirements between START and STOP signals. This can vary by the measurement mode being used so I recommend looking at the data sheet for this. One item that I will point out the though is the length of the START and STOP pulses. They must be at least 10ns. But as far as drive current this isnt something that I have tested in the past or listed in the datasheet, the customer could always test the MCU they attempt to use.

    Best,

    Isaac

  • 0 in reply to Isaac Lara
    Intellectual 506 points

    Sorry for the unclear description about Q2. It is just like you assume that way.  Thanks.

  • +1 in reply to Ryan Lee TW
    TI__Mastermind 19640 points

    Hello Ryan,

    We do not have a flow chart for this but the data sheet does include the steps that should be taken in a measurement sequence. You can find this in section 7.4.6 of the datasheet. I have included an excerpt below:

    Best,

    Isaac