Manual Feeding
When a feed is made by pressing the feed button on the ESP8266 module box there is a short delay while the stepper motor rotates the feeder flaps.
Once the stepper motor stops the ESP8266 module sends a signal back to update the "Man Trigger" count ,take a feed off the current Hopper value
and update the "Last Time & Date Fed" . The bar counter drops 1 feed level as well.





Electronics
I have used modules where possible to keep the design and construction of this project as straight forward as possible.
Veroboard is used to mount some of the components/modules there is no PCB layout or design.
I have used a fuse on the main 12v input to this project. The power cable is rated at 2 amp and I have used a 1 amp fuse. I have also fitted a thermal fuse attached
to the stepper motor housing as as additional safety device. The measured current draw with motor running and mobile phones running as IP servers is 250mA.

ESP8266 module
The ESP8266 module contains a CP2102 chip to allow direct programming via Arduino IDE from a Windows PC or Mac.
Specification:
Chip Module: CP2102
Working temperature: -40 ℃ ~ + 125 ℃
Power input: 4.5V ~ 9V (10VMAX), USB-powered
Current: continuous transmission: approx. 70mA (200mA MAX), Standby: <200uA
Size: approx. 45 x 25 x 6mm/1.77 x 0.98 x 0.23''
Weight: approx. 6g



Voltage Regulator Module LM2596
Power for the L298N, ESP8266 module and the Samsung S3 mobile phone is delivered by a LM2596 DC to DC converter.
 The 12v feed used by the stepper motor is dropped down to 5volts.
The circuit uses 160mA with the mobile On (display off) and the video server app running.
This rises to 250mA wit the the stepper motor running.
Voltage Regulator Module LM2596
Specifications:
Rectification mode:Non-synchronous rectifier
Module property:Non-isolation buck
Input voltage:4V-40V
Output voltage:1.5V-34V(Adjustable)
Output current:Rated current is 2A,maximum 3A(Additional heatsink is required)
Conversion efficiency:92%( highest )
Switching frequency:65KHz
Output ripple:30mV( maximum )
Voltage regulation:± 2.5%
Load regulation:±0.5%
Dimension:43mmx21mmx14mm(LxWxH)





Motor Drive Controller Board Module L298N Dual H Bridge DC Stepper
Specifications
L298N as main chip

High working voltage to 46v,large current can reach 3A MAX and continue current is 2A, power to 25w.

Can drive one 2-phase stepper motor, one 4-phase stepper motor or two DC motors.
Built-in 78M05,get power from drive power, however, when drive power is over 12V,  use the external 5v power as power supply.

Large capacity filter capacitance, back EMF protection diode, more stable and reliable.

Specification:
Double H bridge drive
Chip: L298N (ST NEW)
Logical voltage: 5V
Drive voltage: 5V-35V
Logical current: 0mA-36mA
Drive current: 2A(MAX single bridge)
Max power: 25W
Size:43 x 43 x 26mm(LxWxH)

Note:
This module has a built-in 5v power supply, when the driving voltage is 7v-35v, this supply is suitable for power supply
DO NOT input voltage to +5v supply interface, however leading out 5v for external use is available.
When ENA enable IN1 IN2 control OUT1 OUT2
When ENB enable IN3 IN4 control OUT3 OUT4





Module and Board Layouts


The modules are housed in Perspex topped boxes
The LN298 H Bridge stepper motor module and DC to DC converter in 1 box.


The ESP8266 module is housed in the 2nd box



2nd box with ESP8266 module removed to show Vero Board layout


Vero Board Layout of Fuse Board



Rear of Fuse Board



Cutaway below shows position of fuse board above stepper motor.



Stepper Motor
This is a short geared NEMA 17 Stepper motor. It has an integrated planetary gearbox with a 26.85:1 gear ratio, the resolution reach 0.067°step angle.
It's a good solution in applications that need very low rotation speeds and/or lots of torque.
I tried an identical motor without the gearbox and it was OK until I added the pet food into the hopper then it jammed.

Make sure the mounting bracket has the inner set of drillings if you use this type of motor with a gearbox.

My Stepper Motor Specs
Manufacturer Part Number17HS13-0404S-PG27
Motor TypeBipolar Stepper
Step Angle(W/O Gearbox)1.8°
Holding Torque3Nm
Rated Current/phase0.4A
Phase Resistance30ohms
Recommended Voltage12-24V
Inductance34mH±20%(1KHz)
Gearbox TypePlanetary
Gear Ratio(Exact Gear Ratio)26 + 103/121
Efficiency81%
Backlash at No-load<=1°
Max.Permissible Torque3Nm(425oz-in)
Moment Permissible Torque5Nm(708oz-in)
Shaft Maximum Axial Load50N
Shaft Maximum Radial Load100N






Motor Shaft Coupler
The stepper motor is connected to the feeder d shaft by a motor shaft coupler.
Couplers come is most sizes, my motor has a 6mm shaft and the feeder has a 8mm shaft.



Schematic
Note Thermal fuse F1. This is attached to the stepper motor body above the coils with wire to form a good physical bond.

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