Stackduino SMD

Pcb layout, measuring approx 75x65mm. The successor to this board is here: www.flickr.com/photos/reallysmall/14346062007/

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Stackduino SMD is the next step from the original Stackduino (reallysmall.github.io/Stackduino/). Stackduino is an open source motion controller, designed primarily for focus stacking, which interfaces with a stepper motor, limit switches and a camera shutter.

 

Key development targets for Stackduino SMD are:

 

1/ A smaller footprint

2/ More efficient use of battery power

3/ Provision for future expansion of functionality

 

Power

 

Automatic switchover between ac adapter and batteries is supported by an LTC4412 and Mosfet at a much lower forward voltage drop than using diode ORing for greater efficiency of battery use.

 

Step-down to 5v is handled with a LM2675 buck converter for considerable efficiency improvement over the standard linear regulator used in Stackduino 1.

 

Power on/ off is supported by the LTC2950 pushbutton controller. This also interfaces with the micro-controller to allow the system to switch itself off.

 

Core functions

 

MCP23017 port expander allows software control over most stepper driver functions, power monitoring and system switch-off.

FT232RL interfaces microcontroller with onboard usb port for simple reprogramming.

16x2 parallel lcd replaced with 128x64 OLED, which is more feature rich, smaller, uses less pins and less power.

 

I/O

 

Stackduino 1's DB9 port replaced with a DB15 port, supporting signals for:

 

Ground (3)

Stepper motor (4)

Limit switches (2)

Focus and shutter (2)

Digital pin (2 - currently unused, to support future functionality)

Analogue pin (2 - currently unused, to support future functionality)

 

Done