Laser Power Supply Interface PCB

Laser ps LCD



I want to combine all the circuits I have created for my laser power supply into one interface PCB. This project is attempting to do that.


It is planned to have the following features.

  1. Cooling
    1. Measures the flow using the Koolance flow switch
    2. Adjustable safe flow rate through pot setting. Allows it to be stup for different flow requirements.
    3. Sets fault on power supply water pin on low flow
    4. Blinks the LEDS on the flow switch. The flow switch has some blue LEDS in it. I will hook into these and use them as a visual flow feedback. I am not exactly how I will use it yet.
  2. Laser Power Control.
    1. Digital pot sets power level.
    2. Converts Mach3's slow PWM to a real 0-5V level at the power supply.
  3. Power Supply Enable
    1. Monitors this line from Mach3
  4. Power Supply Status to Mach3
    1. Sets an input pin that Mach3 can monitor about status of power supply. This will let mach know when the power supply has benn shut down for flow or safety interlock reasons.
  5. Interlock Switch circuit
    1. Cover, door, Emergency switches can be looped through this circuit for safety off purposes.
  6. LCD Display
    1. Shows flow as a percentage of fault level. 120% would mean the flow is 20% above the point at which it will fault.
    2. Shows current power level.
  7. RS232 Interface
    1. Status output
      1. Flow rate
      2. Power Level
      3. Enable status
    2. Future Modbus interface


Ciruit Design

I am planning to use a PSoC CY29466 microcontroller. I am using this because I have a development kit for it (PsoCEval1) and I always wanted complete a project with this family of microcontrollers. The PSoC chips are Programmable System on Chip microcontrollers. They combine digital and analog features on a single chip. The nice thing is you can completely reroute just about everything to any pin you want. This makes it very easy to change things around later.


Here is the schematic. This will likely change several times before the project is done.

Laser Power Supply Interface Schematic


More Prototyping

I built a flow switch simulator that can simulate the output of the flow switch. It has an adjustable frequency out from about 3 to 150Hz. That should cover the range I plan to cover. I build it with my MikroElectronica EasyPIC4 prototype board.

I also got some more done on the power supply interface circuit. It now reads the desired flow rate from the pot. I don't have the digital pot yet, so I think I will work on monitoring the flow switch.



I am prototyping the circuit on the PsoCEval1 development kit. So far I have the LCD and the UART (RS232) working. These are not the most important items, but they can provide good debugging output while working on the other areas. I plan to use the Microchip MCP41010 256 step digital pot, but I don't have one yet. I have some on order from Allied Electronics.

Development Board





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