A programmable hardware trigger

These are devices that accept encoder input (eithersingle-ended to differential) and issue a pulse when the encoder reaches a certain position.

These are useful for things like camera triggeringapplications, say for example triggering a camera accurately when a multi-axis stage reaches a certain position.

Ideally, a trigger would be able to accept at least 3 encoders and have a programmable set of XYZ trigger points.

  • let’s say l have a 2-axis stage (XY) and the motors areconnected to encoders that give position feedback.
  • a programmable trigger would be programmed withlist of XY coordinates. For example, [[100, 150],[230,200l,[300,240l1.
  • When the quadrature encoder hits thefirst position [100, 150], the module creates a pulse (e.g+5V for 100us), and another pulse when the next position is reached etc

This would allow people to accurately trigger actions(for example, activating a camera sensor) when theirstage reaches a specific position, where the stagedoesn’t have to stop.
Reddit Snackatron

Atmega328p + PCA9555

  • PCA9555 具有中断功能。当其输入引脚状态发生变化时,它可以产生一个中断信号。你可以将编码器的输出连接到 PCA9555 的输入引脚,并将 PCA9555 的中断输出引脚连接到 Arduino 的一个中断引脚。这样,当编码器转动时,PCA9555 会产生中断信号,通知 Arduino 处理编码器数据。
  • PCA9555 has an interrupt function. It can generate an interrupt signal when its input pin status changes. You can connect the encoder output to the PCA9555 input pin, and connect the PCA9555 interrupt output pin to an interrupt pin of Arduino. In this way, when the encoder turns, PCA9555 will generate an interrupt signal to notify Arduino to process the encoder data.