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documentation formatting fixes #docs
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pyr0ball committed Oct 12, 2019
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Expand Up @@ -9,6 +9,7 @@ To begin, we start with the piezo element itself, which usually consists of a di
The piezo's output is tied to a high impedance input of an [Operational Amplifier](https://www.electronics-tutorials.ws/opamp/opamp_1.html). The Amp stage takes the signal from the piezo and increases it's voltage by a factor, anywhere between 3x and 11x depending on the `GAIN_F` setting. This amplified signal is then passed through to the third stage. The wire between Stage 1 and Stage 3 is also attached to the output of Stage 2 through a high-ohmage resistor. Adjusting the `GAIN_F` setting is the coarsest and easiest way to adjust the sensor's sensitivity.

Use cases for adjusting `GAIN_F`:

- Sensor is not sensitive enough, or is too sensitive
- Many false triggers during movement

Expand All @@ -19,6 +20,7 @@ Use cases for adjusting `GAIN_F`:
This stage utilizes a combination of a PWM-based DAC, another Amp channel, and a high-ohmage resistor. The purpose of this stage is to provide a "Voltage Floor" or a "Virtual Ground" to the Low-Side input of Stage 3. This stage is governed by the `VFOL` setting. The essential effect of this stage is that any signal input from the first stage that falls below the `VFOL` threshold will be filtered out and suppressed. This setting can be used to address a noisy input signal from too much EMI, static electricity, or other factors.

Use case for adjusting `VFOL`:

- Many false triggers when stationary
- Many false triggers during movement

Expand All @@ -29,6 +31,7 @@ Use case for adjusting `VFOL`:
This stage of the circuit utilized another PWM-based DAC to set a "trigger threshold", which is governed by the `VCOMP` setting. When the input signal from the previous two stages increases beyond the threshold set by `VCOMP`, the sensor's Z-Min signal is tripped and a Z-Min trigger signal is sent to the control board of the 3D Printer. As the Follower's filtering signal is attached to this input through a high-ohmage resistor, the amount of time it takes for this triggering circuit to reset is extended, which further reduces multiple trigger signals from being sent. By default, `VCOMP` is set to 2.85v which should be compatible with even 3.3v systems, but there could be instances where the `VCOMP` setting is higher than what the rest of the circuit can provide, and therefore no triggering would occur, even with valid input.

Use case for adjusting `VCOMP`:

- No triggering from the sensor at all
- Low input voltage

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