Pot on ADC to select index filter
Thread Summary
The user sought to modify a working pushbutton filter selection system to use a potentiometer for selecting different filter presets on the 1701minibz eval board. The solution involved removing the lookup table and adjusting the multiplier and integer source to ensure the correct integer range (0-3) for the index filter and index mux. An offset was added to the Aux ADC output to cover the full range, and the DC integer source was set to 3. The Stimulus-Probe filter simulation does not work for runtime filter selection.AI Generated Content
I had this working swell with a pushbutton on a counter. Now I want a turn a pot and select different filters, sort of like "presets". Clearly I am doing something wrong. What is it? The GPIOs are to turn on LEDs to indicate which index is selected. This project is for the 1701minibz eval board. Table values are 0 0.25 0.75 1. The aux adc is 3.
Hello Bro,
Your design is just about correct. The largest change needed was to remove the lookup table -- it just wasn't needed. Your multiplier and integer source converts the -1701's Aux ADC output from its 0.0 -- 1.0 in 5.23 format to 0 -- 4 in integer (28.0) output. The index filter and index mux both use integer inputs -- i.e., an integer of 0, 1, 2, 3 selects output or preset 1, 2, 3, or 4. Thus the LUT (which converted its integer input to 0.0--1.0 in 5.23 format) was getting in the way.
I also finessed the pot a little by adding a small offset to the Aux ADC output, which insures that the multiplier output goes its full range (the Aux ADC may not reach fully 1.0 when the pot is turned fully CW, and the multiply function doesn't round up). Also, since the desired integer is zero to 3 (not 1 to 4), the DC integer source is correctly set to 3. The modified version of your project is attached.
BTW -- The Stimulus-Probe filter simulation doesn't work in this case, where filter curves are selected at runtime. For more info, see
https://ez.analog.com/message/120089#120089
Best regards,
Bob
Thanks Bob! I had figured out to remove the table but your other pointers are essential too.
Brian
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Thank you,
EZ Admin
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