Hello,
I would like to ask you for help with integration of our external amplifier for TI Ultrasonic flowmeter. We are currently trying to use flowmeter with narrow tube with several reflections. Problem is that the signal received have low amplitude even with maximal gain configured on MSP.
To solve this we made our amplifier.
It's based on one of the reference desings, except that it's doubled and both channels are operating all time.
Schematic and oscillograms and setup pictures are included.
Our questions are:
Is it technically possible to have amplifier like that? We would rather to use amplifier, where it's not needed to switch amplifiers on and off.
What are states of output and input pins during different stages of measurements?
What impedance have input of USS stage.
----
We have MSP430FR6047 based devices.
On MSP430FR6047-EVK we removed resistors connected to pins OUT_CH0 and OUT_CH1, and those pins were connected with wire to external pinheader. Same thing was done to pins IN_CH0 and IN_CH1.
From this pinheader is connected our amplifier via coaxial wire.
On picture 1 is (yellow) signal on pin OUT_CH0, and (blue) signal from amplifier that goes to pin IN_CH1. Pin OUT_CH1 is not connected to amplifier.
On picture 2 is (yellow) signal on pin OUT_CH1, and (blue) signal from amplifier that goes to pin IN_CH0. Pin OUT_CH0 is not connected to amplifier.
On picture 3 is (green) signal on pin OUT_CH1, and (blue) signal from amplifier that goes to pin IN_CH0. All pins are connected and whole thing tends to oscillate.
On picture 4 is (green) signal on pin OUT_CH0, and (blue) signal from amplifier that goes to pin IN_CH1. -||-
It look like the problem is related to MSP MCU, because when I tried to use another half of our amplifier, in direction (MCU)OUT_CH0 -> AMP -> Tube -> AMP - > (MCU)IN_CH1 everything works fine, but without second channel.
