TDC7200: tdc 7200 TOF value issue

Hi Rashmi,

Please post the clock period you are using as that is critical to the calculation of the TOF values. As long as you are using the formula described below then you will get the correct TOF values. The TOF values resulting from these equations are in seconds. 

To calculate flow measurement you need to measure both upstream and downstream of the direction of the flow. The difference in time of flight between the upstream and the downstream values is proportional to the flow rate of the medium. The application note linked below includes formulas for calculating flow rate from the TOF data:

Regards,

Hello Scott,

                   I am using a clock period of 4Mhz so far and if this frequency is not ok to tdc please suggest me how much frequency will be good enough to provide...?  I am using same measurement method and calculation procedure  to get TOF as in the data sheet.

one more question at starting am not writing any values to INT_STATUS after the TOF calculation i am reading INT_STATUS register it is reading 19 value is this acceptable....? 

Regards,

Rashmi HM

Hi Rashmi,

A clock period of 4Mhz will work just fine. The fine accuracy of the TDC7200 is not determined by the clock frequency since it has an internal ring oscillator to count the TIMEx values.

The TOF values you have calculated are correct and are in seconds.

The INT_STATUS register values you are reading are correct, and indicate that the measurement is completed. See the register map below:

Hello scott,

                         Till now i was attached  transducer to the pipe with still water but now i have attached the transducer to the pipe where water flows  but now am not able to receive the TOF values but start,stop,echo are receiving properly as shown in the figure below. I am working with 1MHz transducer and am providing 1Mhz resonant frequency to transducers.tThe clock count i am providing is 4MHz for both TDC1000 and 7200.

In the figure

red signal is stop pulses,

yellow signal is start pulse,

ii)when i set TDC 7200 to measurement mode 1,the readings are as follows:-

CONFIG1=1

CONFIG2=44

INT_STATUS=A

INT_MASK = 7

tof1 =nan

tof2 =nan

tof3 =nan

tof4 =nan

tof5 =nan

Time1= 0

Time2= 0

Time3 =0

Time4 =0

Time5= 0

Time6 =0

clkcnt1= 0

clkcnt2 =0

clkcnt3 =0

clkcnt4 =0

clkcnt5=0

cal1 =0

cal2 =0

iii)When i set TDC7200 to measurement mode 2 the readings are as follows

CONFIG1=3

CONFIG2=44

INT_STATUS=C

INT_MASK =7

tof1 =nan 

tof2 =nan

tof3 =nan

tof4= nan

tof5 =nan

Time1 =0

Time2 =0

Time3 =0

Time4= 0

Time5= 0

Time6= 0

clkcnt1= 0

clkcnt2= 0

clkcnt3 =0

clkcnt4 =0

clkcnt5 =0

cal1= 0

cal2= 0

Is there any mistake in Register configuration...? Please do help to resolve this issue...?

iii) and one more doubt i have that is is the order of register setting is important to get read the TOF values from the register....?