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Film processor POC

POC prototype of film processor for developing drums like Jobo or any other watertight.

Schematic

GND and 5v lines not shown, attach it Arduino, touch sensor and stepper driver.

Arduino ports can be remapped in config.h

          _________________________________________
         |                                         |
         |                                         |
         |             Arduino Nano v3             |
         |                                         |
         |_________________________________________|
            |    |    |                  | 
          D9|  D7|  D6|                D2|
            |    |    |                  |                  __________
            |    |    |                  |                 |          |
            |    |    |                  |_________Signal__|  TTP223  |
            |    |    |                                    |__________|
            |    |    |                  
            |    |    |              ______________    
            |    |    |__Enable_____|              |             
            |    |                  |    Pololu    |_______*         *
            |    |_______Direction__|     Step     |______*  Stepper  *
            |                       |    Driver    |______*   mottor  *
            |____________Step_______|              |_______*         *
                                    |______________|
                                        |      |
                                        ^ =12v ^

BOM

I already had most of the parts, so prices approximate.

Part		Price
Printed parts
Arduino Nano rev 3		~6$
TTP223 touch sensor		~1$
Stepper driver interface board		~5$
DRV8825 or any other compatible driver		~5$
NEMA17 or NEMA14 stepper motor		~15$
GT2 450mm 6mm wide close timing belt		~2$
20T or 36T 8mm bore GT2 pulley X 2		~5$
16T or 20T 5mm bore GT2 pulley		~2$
LM2596 or any 5v step-down converter		~3$
Any 12v 2-3A power source		~10$
Any large enough container
Any enclosure for electronic parts
200mm piece of 8mm stock X 2
Assorted M3 and M4 hardware
	Total:	~60$

Construction

You can drive developing drum in any way you want, even use a lift from Jobo processor if you find one.

Kinematic scheme of my prototype must be a pretty obvious by this picture. Place axis about 100 mm apart.

Firmware

Easiest way to build and upload firmware is using Arduino IDE.

1. Download and install Arduino IDE from official site.
2. Install FreeRTOS library using Sketch->Include library->Manage libraries... Type 'freertos' in search field, in first row select version 10.4.4-1 and click Install.
3. Select your board in Tool menu.
4. Click Upload.

Calibration

Before using this construction you must set a number of motor steps per one full rotation of particular developing drum.

Manipulate value RATIO in config.h until drum can make TURNS rotation without significant error.