Hi team,
The ultrasonic water flow meter MSP430FR6005 solution is having a problem running at large traffic.
When small flow is slowly increased to large flow, it is now working properly.
1) While the following problems occur when running large traffic first and slowly reducing traffic:
a. The error in the measurement is very large, at about 8734 208 (which is expected to be within 3,000) when still water, and no error is reported.
b. USS_message_code_HSPLL_verification_expected_count_error(27) is returned when calibrating the crystal using USS_verifyHSLLFrequency
c. USS_message_code_Signal_gain_Calibration_timeout error returned when using USS_calibrationSignalGain to calibrate AGC
d. Use an oscilloscope to measure the wave form of the transducer and crystal, and visually inspect the wave form and frequency are good.
2) After flushing the flow, it returns to the still water, and the time difference is abnormal. Analyzing the time difference data found that it was overlaid by approximately 0.5 us.
3) HW resources:
- CPU: MSP430FR6005
- USS: Crystal uses 8 MHz (Chip Ceramic Resonator, CSTNE8M00G520000R0,8M,10 pF (built in), accuracy ±0.5%)
- Matching capacitor: Chip ceramic capacitor, 12pF(120), 50V, ±5%, 0603, NPO, -55~125℃
4) Reproduce:
Currently, NPO 12pF is used for matching capacitor in USS section, which can be more easily reproduced by changing the matching capacitor to 20pF. After the matching capacitor is reduced, it is hard to reproduce.
Could you help check this case? Thanks.
Best Regards,
Cherry
