Open Documentation

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====== LogLED ======

LogLEDs are a series of open-source LED circuits or drivers for R30 LED emitters intended for scientific and industrial use. They are PapaLink compatible devices developed and manufactured by DEV Joni.

Current product lineup

  * LogLED 311
  * LogLED 116
  * LogLED 111
  * LogLED 103

===== Technical aspects =====


==== Accurate timining ====

LogLEDs can change the brightness of the R30 LED precisely but there are some caveats.

Directly over the PapaLink (I2C) connection, it is possible to control the driver "on-the-fly". Usually, the time latency accuracy here is from 1 ms to 20 ms depending on your OS and its scheduler. More accurate way is to move the control of the timing and commands to the PapaLink controller but then much flexibility from running the program on PC is lost.

The baseline frequency for PapaLink (I2C) is 100 kHz. It theoretically allows ~5 kHz operation for 2 byte commands (8-bit address frame and 8-bit data frame, 2 ACK/NACK bits, 1 stop bit, 1 start bit) when controlling one device.

Over the BNC port, for a trig-in or LED-on/off signal , digital readout in the best case can be done within 5 µs - nearly instantaneously compared to the delay setting the LED on/off. However the complexity of the running program will induce considerable overhead on this number. Also, when using this method, the pulsed pattern has to be small enough it fits to micro-controller's SRAM or it has to be generated