Talking Darkroom Timer
I got tired of having to mess with darkroom timers in the dark while processing colour prints in trays, so designed and built a timer that understands entire processes and walks you through them step-by-step with speech. The timer reads process information from paper instruction sheets using Aztec 2D barcodes and then times each required step.
- Timer itself, located above the left side of the sink near the ceiling
- Raspberry Pi 2
- Adafruit LCD Plate
- Proto Plate with RS232 level shifter for barcode reader
- Speaker above the timer
- 2D barcode reader mounted on the shelf aimed at the wall
- Control panel below the sink with the following controls:
- Large green SELECT button
- Navigation left/right control
- Active/Standby toggle switch
- Aztec Code barcodes on each process sheet, which contain all timing information
- Set the Active/Standby switch on the timer control panel to Active
- Scan the barcode for the process you want under the crosshairs that appear on the wall
- Barcodes can be found on instruction sheets for each process that are hung up behind the door.
- Double check that the timer is displaying the process you want to run, and press the big green SELECT button
- The timer may ask if you want to adjust the time for specific steps.
- If you don't, just press SELECT.
- If you do, use the navigation buttons to change to Yes and press SELECT.
- The timer will show and read out each step as it's ready.
- Press SELECT to start each step.
- If you want to run a different step instead, use the navigation buttons to scroll through.
- To abort a step in progress, hold the SELECT button until you hear a buzzer.