PI A+, B+, 2, 3
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This project combines a whole heap of modules to enable a Raspberry Pi to power a large 1.2 inch 4 digit 7 segment display. A small switch switches the display between showing the temperature and the current time. The project uses a real-time clock (RTC) to ensure that the Pi always has the correct time, even if it is not connected to the Internet.
This new Adafruit Pi Plate makes it easy to use an RGB 16x2 Character LCD. We really like the RGB Character LCDs we stock in the shop. Unfortunately, these LCDs do require quite a few digital pins, 6 to control the LCD and then another 3 to control the RGB backlight for a total of 9 pins. With this in mind, we wanted to make it easier for people to get these LCD into their projects so we devised a Pi plate that lets you control a 16x2 Character LCD, up to 3 backlight pins AND 5 keypad pins using only the two I2C pins on the R-Pi!
To keep costs low, the Raspberry Pi does not include a Real Time Clock module. Instead, users are expected to have it always connected to WiFi or Ethernet and keep time by checking the network. Since we want to include an external module, we'll have to wire one up. We'll go with the easy-to-use and low-cost DS1307.
In this tutorial we'll be showing how to utilize a DHT sensor Python library based on C for high-speed GPIO polling to handle bit-banged sensor output. Many low cost sensors have unusual output formats, and in this case, a "Manchester-esque" output that is not SPI, I2C or 1-Wire compatible must be polled continuously by the Pi to decode. Luckily, the C GPIO libraries are fast enough to decode the output.
Once soldered together, the cable plugs between the Pi computer and the Cobbler breakout. The Cobbler can plug into any solderless breadboard (or even a prototyping board like the PermaProto). The Cobbler PCB has all the pins labeled nicely so you can go forth and build circuits without keeping a pin-out printout at your desk. We think this will make it more fun to expand the Pi and build custom circuitry with it.