Part Number: MSP430FR6047
Other Parts Discussed in Thread: TIDA-01486, THS3095
I have recently designed a "UltraSonic Flow Meter" based around the MSP430FR6047 that uses external switches and amplification circuitry, almost identical to the TIDA-01486 TI Ultrasonic Flow Transmitter Reference Design. The external switch and amplification circuitry allows for 4 Ultrasonic Flow Sensors (US0014-001) to be connected and driven at their maximum voltage (5Vpp).
An ADC Capture reveals the following:
I believe the contention between the external DC-Bias that I'm applying to the Non-Inverting Input of the Rx OpAmps (THS3095) and the Rx-Bias applied by the MSP430 during signal acquisition is the reason the signals are not centered around 0 Amplitude. An over-voltage of the ADC input may also be occurring but I believe this can be handled by decreasing the gain of the external Rx OpAmps and/or Internal PGA.
The issue our software engineer has encountered while attempting to disable the internal Rx Bias applied by the MCU is detailed below.
We are running a modified version of the 'MSP430FR6047EVM_USS_Water_Demo' example program.
We've modified the SAPH initialization function, USS_updateSAPHConfiguration() in USSSWLibConfiguration.c in an effort to remove the DC bias.
