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Raspberry Pi

11 Posts authored by: mistertee
Like all PCs the Raspberry Pi is likley to hang up during operation due to unexpected events not being catered for in the code. In an unattended application where the program automatically starts this can be a problem as there is no one around to restart the RPi. If there is no keyboard or HDMI monitor this is by power cycling. The Raspberry Pis internal watchdog timer has a poor reputaion - there are many comments about it being unreliable. This post presents a simple external watchdog timer. & ...
Remote control of pumps, heaters, lights and other appliances is often a requirement in Home Automation, Building Control or Automation of Industrial Control processes. Traditional radio modules can often disappoint by having poor range or being prone to interference. FM Radio Modules when compared to much cheaper AM modules gives superior performance in both these areas. This post is about a remote module that has two independent relays for remote switching ON and OFF of appliances.   &# ...
When putting together a Home Automation System together it is often necessary to gather analogue data. This could be from temperature / humidity sensors or to measure battery voltage. Often these are remote to the computing module which could be a Raspberry Pi, and Arduino or a PC - for example when gathering data from a weather station on the roof of a building.   This example below shows how the DART and the URR could be used to gather useful information from around the home.   &# ...
This post shows how to use the Dual Analogue Radio Transmitter (DART) and the Universal Radio Receiver (URR) to monitor the temperature of one or more freezer.   The DART collects data from 2 analogue inputs and transmits this to a receiver using a 433 MHz FM radio module. (FM radio modules gives gives significantly better range and noise performance when compared to AM modules). More information on the DART and URR can be found here.         The TMP36 is very easy to ...
The Custard Pi 3 plugs into the Raspberry Pi GPIO (A, B, B+ and 2) and provides 8 analogue inputs using the SPI bus. This post shows how you can connect 2 x Custard Pi 3 to a Raspberry Pi and get 16 inputs. (There is soldering required). The Custard Pi 3 uses the SPI bus. The connections are shown below. J1-24 is the chip enable (CE0) output from the GPIO which is used to address the AtoD chip - MCP3208. The other pins are   J1_19:  MOSI - data out from the GPIO (input to ...
Over the last 2 years we have created some great projects and tutorials for the Raspberry Pi GPIO. These are great for hobbyists, and for students. Here are some highlights.   Electronic Dice project including soldering and Python coding   Using the Mains Switch Widget to switch 4 mains powered appliances  Weighing scales using the Custard Pi 3   Sending an e-mail from the Raspberry Pi   Switching an appliance ON and OFF with an e-mail   Autostarting a Python p ...
Mixing and Matching Custard Pi’s   Introduction   If a particular Custard Pi does not have all the right inputs and outputs, then it’s possible to combine more than one. This post looks at the various combinations that are possible.   For more examples click here to go to the blog post   GPIO bus connection method   The various cards use different means of connecting to the Raspberry Pi GPIO and this summarised below.   SPI bus I2C bus 8 digital I/O C ...
When working with analogue signals, scaling them to the correct range for the Analogue to Digital Converter (ADC) is always important. Below are some projects that will help anyone starting in this area.   Project 11 - Using the Raspberry Pi to measure temperature Outline This application note shows the hardware and Python code required to measure temperature using the Raspberry Pi. Any of the Raspberry Pi models can be used including B, B+ and the Raspberry Pi 2.   In this projec ...
This design uses a Load Cell, an op-amp and the Custard Pi 3 with a Raspberry pi to measure weights.   The circuit is presented below     For full documentation and sample Python Code go the SF Innovations Tutorials page and click on the Custard Pi 3 weighing scales project.   The sample Python code can be downloaded from the SF Innovations Downloads page  ...
I was keen on turning things ON and OFF remotely by sending an e-mail to the Raspberry Pi. The Mains Switch Widget (MSW) allows me to easily plug in an appliance and use the Raspberry Pi to control it. I looked at Twitter and then text messages to control the MSW. Twitter did not allow me to send the same message twice, which was kind of essential to send ON and OFF commands. Text messages looked a little complicated with either a GSM connection or some sort of text to e-mail service.   Co ...
This is a hardware hackers dream with a host of features built in as shown below.       2 Relay outputs 4 Open Collector outputs 2 Built in Switches 8 General Purpose Digital I/O 4 Analogue inputs 1 Analogue output 16 pin LCD Interface LED indication on most ports Screw terminal connection on most ports Flexible Power Supply   Board can be powered from Raspberry Pi   Board and Rpi can be powered from 5V supply   Board and Rpi can be powered by 2 separate 5 ...

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