This is a proposed project to create a system based on KFLARE which would provide single-channel Laser/TEC driver boards controlled by a single central controller. Some notes:

  • Existing design uses an Atmel ATMega164A uC per laser in a 44-VQFN package. This device is efficiently used, with only about 4 spare I/O pins.
  • Communication is over a Modbus-like RS-485 serial shared bus. This works well since RS-485 has very good power supply rejection. See communications protocol spec document.

In the current system an additional ATMega64A uC was used as the system controller, which would manage up to 20 Laser/TEC modules and handle the interface with the host computer. The system controller also managed the power supply, fans and an additional white light source.

System Controller functions:

  • UART (RS-485) bus to Laser/TEC modules
  • UART or other interface to host computer
  • Fan control PWM output
  • Fan sense input
  • Interlock control logic inputs: TEMP_ALARM, AC_FAIL, FAN_FAIL, INTERLOCK_STATUS
  • Interlock control logic outputs: LASER_SHUTDOWN, LASER STATUS (per laser)
  • ~4 temperature sensors
  • I2C DAC for laser current setting (or maybe Laser/TEC control?)
  • White light source control (opt-isolated)
  • Laser enable outputs
  • LED indicators

Suggest to keep the Laser/TEC as-is and possibly update the system controller. Some options and pros/cons:

  • Zynq, e.g. Enclustra Mars ZX2 DIMM
    • Pros: Linux on-board, familiar, lots of GPIOs, complete control of peripherals
    • Cons: Analog inputs may be hard to use
  • Beaglebone:
    • Pros: Linux on-board, UARTs and analog inputs built-in, enough GPIOs
    • Cons: Unfamiliar, sounds like analog inputs are a real headache
  • Raspberry pi:
    • Pros: Linux on-board, widely used
    • Cons: Unfamiliar, share UART with serial console (?), analog inputs maybe a pain
  • FPGA Eval board:
    • Pros: Relatively easy to use (IPBus interface?)
    • Cons: Need to come up with an ADC solution

There exist some useful PMODs, such as Isolated RS-485 and 4 ch 12 bit ADC

Last modified 7 months ago Last modified on Apr 2, 2019, 10:24:18 AM