All posts by Peter Ogden


Network PDU-S: Schematic

Circuit Design

The Network PDU-S will be based on the Arduino Ethernet board, however instead of the ATMega328 I’m going to use an ATMega2560.  This is the same chip that is used in the Arduino Mega, and I’ve used it in several designs before so I’ve already got most of what I need to create the schematic.

For the Ethernet controller, I’ve chosen to use the same Wiznet W5100 chip as the Arduino Ethernet so I can take advantage of the existing code libraries.

I’m including a Max232 RS232 to TTL level converter in the design.  This will be used for debugging, and possibly included in the final product to send/receive commands to RS232 compatible devices.


Here’s the top level schematic designed in Kicad:


Network PDU-S: High Level Design

Design Requirements

1. Its simplest function is power distribution.  the Network PDU-S  will provide a 6rear + 2front outlet power strip.

2. This device includes a programmable sequencer that allows you to power equipment on/off in a specific order.

3. This device includes network control.  From a webpage you will be able to configure the sequencer settings as well as toggle individual outlets on and off.  The device will also be able to send commands to other sequencers allowing you to control the power-up sequence of equipment at remote locations via the internet.

Motivation for this project

1. I travel a lot for work, and sometimes I need to remotely power cycle the servers in my home data center.

2. For my A/V work I need a power sequencer to turn on the sound board and amplifiers in a specific order to avoid equipment damage.

3. In some A/V venues I need to sequence equipment in the sound booth, on stage, and also back in electrical rooms.

4. I would like to get per-outlet power metering so I can closely monitor peak/average power consumption of all of my equipment.

 High Level Design Document

High Level Block Diagram

I created this diagram with DIA diagram tool..


Wireless Garage Door Opener

Xbee Home Automation

Yet another XBee based home automation device: A wireless garage door opener.

This is exactly the same as the sprinkler controller, except I am using an old cell phone charger as the power supply and I’ve added some limit switches to detect the door state.

Just like the sprinkler controller, my home automation server sends AT commands to control the XBee line states.

A very minimal web interface completes the project for now.

Wireless Garage Door Opener
Connected to the normal garage door opener
Limit Switch Detects Door State

Home Automation Web Interface


Sprinkler Controller

4Channel Xbee Sprinkler Controller

I built this simple XBee based sprinkler controller for my home automation system.  Its so basic there is no schematic.

The digital IO lines on the XBee to drive a few TIP120 darlington transistors I had in my parts box.  No extra logic or firmware required.

A salvaged power switch and IDC connector bring power into the box.  The large transformer and bridge rectifier are all it takes to power the solenoids.  A linear regulator and some caps feed the XBee.

Software wise, I’m just using a cron job to trigger a script that sets the XBee IO line state.

Closeup of the Circuit Board

Ready to close up

Finished Sprinkler Controller


Preschool Gate Controller

Use Cases

Entering the Main Gate

A.      A valid code is inputted via the keypad.
1.       Press “Start” on the keypad.
2.       Type in the 4digit code on the keypad.
3.       Press the “OK” button.
4.       Door unlocks for 30seconds.
5.       Door relocks.
B.      An invalid code is inputted via the keypad.
1.       Press Start on the keypad.
2.       Type in a wrong code on the keypad
3.       Press the “OK” button.
4.       Door remains locked.
5.       The doorbell chime rings to let the office staff know someone is having trouble.
C.      Office staff buzzes someone in manually. Note: This is the existing use case
1.       Guest presses “Doorbell” button on the keypad.  The doorbell chime rings.
2.       Office staff visually authenticates the guest.
3.       Office staff presses one of the red buttons at their desk.
4.       Door unlocks for 30seconds.
5.       Door relocks.
D.      Fire authority uses key to disarm the gate in the event of an emergency.
1.       Fire authority turns key
2.       Door unlocks
3.       Alarm goes off in office.
4.       Door remains unlocked until the key is used to rearm the gate.

Exiting the Main Gate

A.      Authorized Exit
1.       User presses the green button.
2.       Door unlocks for 30seconds.
3.       Door relocks.
B.      Unauthorized Exit
1.       User presses the touch-bar. Note: The touch-bar contains a touch sensor.  This is a safety feature to allow people to escape in the event of an emergency.
2.       Door unlocks.
3.       Alarm goes off in office.
4.       When the door is closed, the alarm goes off.
5.       Door immediately relocks.

Entering the Far Gate

A.      Key is used to unlock gate
1.       User unlocks the gate with the key
2.       Door unlocks (mechanically).
3.       Alarm goes off in office.
4.       When the door is closed, the alarm goes off.
5.       Door immediately relocks (mechanically).

Exiting the Far Gate

B.      Unauthorized Exit
1.       User presses the push-bar.
2.       Door unlocks (mechanically).
3.       Alarm goes off in office.
4.       When the door is closed, the alarm goes off.
5.       Door immediately relocks (mechanically).

Arming/Disarming the Gate

Arming/Disarming the gate is done via the toggle switch on the right side of the gate control box in the preschool Front Office closet.

System Components

The Gate System consists of several components

  1. Door-Open Sensors
  2. Procare KEIS Entry Keypad
  3. Securitron Touch Bar
  4. Securitron Electromagnetic lock
  5. Alarm
  6. Door Bell Chime
  7. Brainbox Network RS232 Adapter
  8. Doorbell transformers
  9. Exit button
  10. Entry “buzz” style buttons
  11. 555 timer
Gate Controller System

The wiring for all these components are brought to a secured electrical box.   Most of the components are connected in wired AND/OR configurations that allow different parts of the system to deactivate the magnetic lock or activate the alarm.

Assembled PCB

Originally I was using screw terminal strips and doing all the wiring with jumpers, but this got pretty messy with all the connections.  To clean things up I designed a simple PCB.


Wired Projector Remotes

Remote Control Panel

I created this wired projector remote panel for my church to make it easier to control the projectors.  No longer must we struggle to configure the projectors by waving around the IR Remote.

I installed a cat5 cable that breaks out 1 twisted pair at each of the projectors.  All 3 projectors share a common ground..

The white box on the left is a Keystone jack box with an RJ45 keystone jack installed.  Each remote has a 1/8mini jack that is terminated to one of the pairs of the RJ45 keystone jack.

As finishing touch, the remotes are mounted on a board that I wrapped in some black felt that was left over from building my sound rack.

In the future I would like to figure out the signaling used by each of the remotes and create my own custom controller.  This would let me perform actions like freeze and blank to all 3 projectors simultaneously similar to what  you would get from a video switcher.

Projector Remote Panel