My Pi Has Arrived
It's Chrismas in July! My Raspberry Pi has finally arrived. Setup was pretty easy:Standard cell phone charger (micro USB) at least 700mAeither an HDMI or composite video connectionUSB keyboard and...
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Raspberry Pi Serial Port
Prototyping the serial port interface.Many of the GPIO pins on the Pi have other special uses. The most useful of these are the serial port pins #8 and #10, which are transmit and receive for an...
View ArticleAlways Sage Advice - Use Protection
If you read any about interfacing to the Pi GPIO pins you are bound to come across the dire warnings - BeCareful. These pins connect directly to the microprocessor without any protection. You can...
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GPIO Input Circuit
After holidays and many other distractions, I am finally able to get back to work on my Raspberry Pi interface. Here is the GPIO input circuit that I came up with using an opto-coupler for protection....
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GPIO Output Relay Interface
Note: See my revised relay circuit here.To allow the greatest flexibility, my outputs are all relays. This allows me to switch a variety of voltages and provides protection to the GPIO pins of the...
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So Many Inputs, So Few GPIO Pins
I keep coming up with so many improvements to my interface design (I'm up to version 6 now) that I'm not getting much built. I decided that I had to make the pins for the SPI and I2C buses available....
View ArticleGreat Article on Designing the RasPi
Wired has a great article by Pete Lomas, a co-founder and trustee of the Raspberry Pi Foundation, where he describes the design process for the Raspberry...
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Revision to Relay Circuit
I have used the relay circuit from my earlier post many times and I know that it works. However, I have seen that circuit drawn with a 1KΩ resistor and also with a 10KΩ resistor and started to wonder...
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Folder Paper Case
I saw a post on the RasPi forum today about a new folder paper case and I thought I would try it out since my RasPi number 4 needs a home.http://www.iammer.com/raspi/case.htmlI printed it on heavy card...
View ArticleSource Code - Installment One
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Interface Nearly Complete
After far too many revisions, the GPIO interface for the Raspberry Pi alarm system is nearly done. It has:• 8 Digital Inputs• 4 Relays• 1 RS-232 serial port• 2 SPI bus connectors• 1 I2C bus...
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Interface Completed
After yet another design change, I finally have the interface complete and ready to test.Version 7 Finally Comes to Life ✓ Serial Port ✓ 8 Digital Inputs ✓ 4 Relay Outputs...
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Mounted and Testing Begun
The interface is complete now with all (well, most anyway) of the kinks out of it. Here it is mounted on the wall in a utility area of the house.I still need to install a few more sensors for the...
View ArticleDual power supplies is the way to go
You may notice in the picture of my setup (in the previous post) that the Raspberry Pi is being powered normally via the USB power connector. This was done because the Pi was failing to boot when...
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Analog Interface
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Reading Temperature With Thermistors
My first interest for an analog input is a probe to read the temperature in my beer fridge. (I am a home brewer and occasionally need closely controlled temperature for fermenting lagers.) There were a...
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All cleaned up and re-mounted
A nice clean board (actually, i just flipped the old one over) and all components re-mounted. System is up and running 24/7 now.The Cleanly Re-Mounted Alarm/Automation System
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Jumbo Digital Picture Frame
What do you do with a spare flat panel monitor? If you are a Raspberry Pi hobbyist, you turn it into a jumbo size digital picture frame. Photography is another of my hobbies and this is a great way...
View ArticleLow Memory Automatic Reboot
Below is my solution to the memory leak problem that I discovered in the frame buffer interface used by my digital picture frame. My first thought was to simply schedule a reboot at midnight, but the...
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USB Hub Modified to Back Feed Power
Most powered USB hubs will not feed power back into the host system. This is normally a good thing. However, it is possible to power the Raspberry Pi by back feeding power from a powered USB...
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