DoorContoller

Hen house door controller

NOTE:

Set attiny clock speed to 1Mhz and re-burn the bootloader (Options on Tools menu of Arduino IDE). Faster speeds mean the interrupt timer runs faster and screws up my timings.

Requirement

• Minimal power consumption
• attiny85 at heart of it
• Everything controlled by interrupts
• Separate door control logic from compute (save on attiny85 outputs)
• Average light readings over 5min period
• Open door if light level above x
• Close door if light level below y (lower number than x)
• Button to override door open/closed and stop logic

• Press 1) disable logic, swap door state
• Press 2) enable logic, swap door state

• If door open, LED on
• Go to sleep when nothing is happening

Components

• attiny85 microcontroller dip
• Inverter logic dip 74HC04
• AND logic dip 74HC08
• Momentary push button
• LED
• LDR
• Magnetic reed switch (NO) x 2
• L298n motor controller
• 12v DC motor 2.1kg lift 70rpm
• Resistors (10k ohm x 4, 460 ohm x 1)
• Smallish breadboard x 2
• Lots of jumper cables

Door Controller Logic Circuit

• One digital input at either high or low
• High means door should be open
• Low means door should be closed
• Two reed switches at top and bottom of door, using 10k ohm pullup resistors
• Magnet in door positioned so opposite reed switches when open / closed

Logic

• If input is high and top reed is open, rotate upwards
• If input is low and bottom reed is open, rotate downwards
• All other states, motor off

Circuit diagram for drawio

Compute Module

Wiring

Connections to attiny85

• Pin 8 (VCC) - 5v power
• Pin 7 (PB2, INT0) - Button output with 10k pulldown resistor
• Pin 5 (PB0) - LED with 460 ohm resistor (anything 300 - 1k, just changes brightness)
• Pin 4 (GND) - Ground
• Pin 2 (PB3, ADC3) - LDR with 10k ohm pulldown resistor

Circuit diagram for drawio

Logic

• Monitor LDR every 30s and store value in rotating array of 10 values, giving 5mins of values
• Check average of values every 5mins and set controller output to high or low

• Value below x, set controller output low
• Value above y, set controller output high

• Set LED to high / low, same as controller output
• Override button:

• Press 1) disable logic, swap controller output
• Press 2) enable logic, swap controller output

Soon to come

• Send door opening / closing signal via 433Mhz transmitter
• Send state every 5mins via 433Mhz transmitter