Hi everyone, I would like to build an Arduino automated macro-photography rail (let's call it AAMR). I'm a decent software engineer and I want to learn electronics, so I'm looking for someone telling me I'm going in the right direction... The idea sounds simple, I want to : 1/ place the subject on the AAMR 2/ input the # of pictures needed to perform a "focus stacking" (https://en.wikipedia.org/?title=Focus_stacking) 3/ push the start button and make the AAMR loop n times through the following steps : - trigger the camera to take a picture of the subject - move the subject 1 millimetre toward the camera After a couple weeks reading and day-dreaming, here are my thoughts. I need : - to read more :) - a steeper motor and its driver (I own bipolar steppers and L298 / L293 IC) - to trigger the camera (Canon EOS 70d : remote cable is quite easy to make) - a potentiometer and 2* 7segment displays (input and display the # of pictures) - a start button - a reset button to make the rail come back at position Zero - two "end of course" buttons (not sure about the English terminology), just in case the motor wants to jump over the board - power (5v for the arduino and the logic, 12v for the motors) I. Arduino ---------- First things first, I plan to use an Arduino Uno during prototyping and replace it by a home made board in the final product. Uno has 14 Digital I/O Pins and 6 Analog Input Pins : - stepper => 6 Digital pins (3 ?? if using http://www.bristolwatch.com/L298N/L298N_arduino.htm) - 7segment led => 3 Digital pins if using shift registers (https://www.instructables.com/id/Different-methods-of-driving-7-Segment-LED-display/step5/null/) - start button => 1 Digital pin - reset button => 1 Digital pin - "end of course" buttons => 2 Digital pins - camera trigger => 1 Digital pin (to drive an opto isolator / solid state relay) - potentiometer => 1 Analog pin 14 Digital pins ! Uno should do the job, am I right ? (I know I could use Analog pins as Digital ones, but it seems I don't need it...) II. PSU ------- Next interrogation is about power supply : I don't want a battery powered device and my options are scarce : - ATX PSU supplies both 5 and 12v, but Arduino seems to like >5v, so ATX doesn't seem a good choice - home made PSU from an existing wall wart -> voltage divider to get ~7v and ~14v -> 7805/7812 voltage regulator (may need heatsinks and/or little fan) If I do the math : - Arduino : 50ma - Stepper motor : 700mA max - L298 : 70mA (quiescent current) - 2* 7Segment LED (multiplexed) : 2 * 80mA (estimated) - Shift registers IC (SN74HC595N) : 1ma (optional : Hex inverter 74LS04 : ?? mA) Total : around 980mA... Am I doing right ? I have tons of questions left (Hex inverter, filter capacitors, motor noise reduction, solid state relays...), but it's a good start :) Sorry for the long post, and thanks in advance for your answers ! D