Analog Signal Processing


#1

Hi everyone, I am in a bit of a bind. We are using an Accelerometer, 0-2000G from TI Connectivity. It is an analog sensor, 3.3 V supply voltage.

https://www.digikey.ca/product-detail/en/te-connectivity-measurement-specialties/834M1-2000/356-1102-ND/2712144

The sampling rate, through ADC is too slow for our application. We are able to get 10,000 samples per second. However, we need 20,000 or greater sampling rate.

As for the application, we do not need to record or write values. In fact, the output of the accelerometer is only important once a set threshold value is reached (its used as an impact counter). For example, 1000G~2.2V… when 2.2 volts is seen, digital ON signal needs to be recorded.

Since its a simple application, I was hoping to bypass ADC completely. I was hoping to take the signal from the accelerometer and put it through some kind of adjustable switch. Once the switch is calibrated to…say 2.2V…it would then be digitally read (with a 48mhz processor) and every time the system hits 1000G, it would digitally trigger and allow the circuit to detect it with a very high speed. Is there such thing as the switch that I am describing?

Thanks for your help!


#3

Hi Serg, One technique is to use a digital to analog converter (DAC) or a simple R2R ladder to track the output of your accelerometer with a comparator that compares the output of the accelerometer with the output of your DAC while your microprocessor continually dithers the output of the DAC to keep the output of the accelerometer “captured.” Of course you can also take the comparator output and feed it into your uC’s interrupt pin to do this interrupt driven. Happy to provide more details if you need them. -RR


#5

A (quad) comparator with one pin set at 2.2V, a simple resistor divider can create that from 3.3V or 5V
Tie the output’s to a mcu timers counter and you will never miss it, even if sleeping.

https://www.digikey.ca/products/en/integrated-circuits-ics/linear-comparators/692?FV=ii4|105%2Cffe002b4%2C1f140000&quantity=&ColumnSort=1000011&page=1&stock=1&k=comparator&pageSize=25&pkeyword=comparator

if you want 3 settings like: 2V, 2.2V and 2.4V, adding a resistor to mcu pin to either add or subtract 0.2V to the resistor divider (as input it leaves it alone)