Dear Sir/Madam,
I am facing some concern regarding PCB trace/signal design when using MCU MSP430FR5989, using 3 LC sensors for a water meter application. The water meter contains of a rotating half-metal disc:
Above is just an example, I am using 3 LC sensors instead.
I completed the design of a testing PCB & performed 2 test cases as follow:
- Test case 01: Test 3 LC sensors, with designed PCB, read out the signals at a LC sensor test point using oscilloscope.
And below is our result when measured with Oscilloscope:
dV is only 80 mV between metal half disc and plastic half disc.
Wave amplitude is reduced between metal half disc and plastic half disc => Can’t detect ESISTOP flag and INT flag of Q6.
- Test case 02: Test 3 LC sensors, with modified PCB (direct wire soldering), read out the signals at a LC sensor test point using oscilloscope.
When they layout the LC sensor to go below the MCU (Test case #1) Vs wire soldering outside MCU (test case #2), they observed the dV measured by oscilloscope at the same test points has higher amplitude (160 mV). Why is it so?
Then the dV measured by oscilloscope at the same test points has higher amplitude (160 mV).
Between the PCB trace (test case #1) vs direct wire soldering (test case #2), we could only observed that PCB trace is routed underneath the TI MCU. But this might not be the cause for lower amplitude on original PCB trace.
Can you help to advice:
- Is the LC sensors signals cannot lay beneath the MCU IC?
- Hence could you please support clarifying if any other element could impact the dV measured at a LC sensor?
Best Regards,
Felix
