6 GUI and Operation

1. If you haven’t done so, open the TDC720xEVM GUI. The EVM GUI software can be run by clicking on Start, then clicking All Programs, Texas Instruments, and TDC720xEVM and selecting TDC720xEVM.
2. Click on the TDC720x tab and make sure TDC1 is selected with the register configuration in Figure 8:
Figure 8. Recommended TDC7201:TDC1 Register Configuration
3. Click on the Graph tab, then click on START GRAPH. You should be able to read 19 µs (assuming you follow the instructions as specified in Section 5.1).
Figure 9. Graphing
4. Calculating Time-of-Flight:
   1. In the GUI, click on the TOF_ONE_SHOT tab.
   2. You should be able to see similar measurement results register values as shown in Figure 10 (assuming you follow the instructions as specified in Section 5.1).
   Figure 10. Measurement Results
   3. To calculate the time-of-flight, use the Measurement Mode 2 Time-of-Flight calculation as shown in Equation 1. For more information, refer to the TDC7201 data sheet (SNAS686).
   4. Use the values reported in the Measurement Result Registers (Figure 10) to validate the time-of-flight as approximately 19 µs (assuming you follow the instructions as specified in Section 5.1).
Equation 1.
where

• TOFn [second] = time-of-flight measurement from the START to the nth STOP
• normLSB [sec] = normalized LSB value from calibration
• TIME1 = time 1 measurement given by the TDC7201 register address 0x10
• TIME_n+1 = (n+1) time measurement given by the TDC7201 register addresses 0x12, 0x14, 0x16, 0x18, and 0x1A
• CLOCK_COUNTn = nth clock count values in register addresses 0x11, 0x13, 0x15, 0x17, and 0x19
• CLOCKperiod [sec] = external CLOCK period
• offset [sec]= constant measurement offset
• CALIBRATION1 [count] = TDC count for first calibration cycle, located in register address 0x1B
• CALIBRATION2 [count] = TDC count for second calibration cycle, located in register address 0x1C
• CALIBRATION2_PERIODS = calibration count bits, located in register address 0x01
Equation 2.
5. START_EXT2/STOP_EXT2 Testing
   1. Modification to Input Signal Connections:
      1. Disconnect USB-to-SMA cable connection to START_EXT1 (J5). Instead, reconnect channel 1 of the dual function generator to TDC7201EVM’s START_EXT2 connector (J8).
      2. Disconnect USB-to-SMA cable connection to STOP_EXT1 (J4). Instead, reconnect channel 2 of the dual function generator to TDC7201EVM’s STOP_EXT2 connector (J7). See Figure 4.
   2. Now repeat steps 1 through 4 from Section 6 with the following modification to step 2: Click on the TDC720x tab and make sure the TDC7201: Select TDCx field is as shown in Figure 11.

Figure 11. Recommended TDC7201:TDC2 Register Configuration