Measuring temperature with the Raspberry Pi

One of my Raspberry Pis is running as a headless device measuring the room temperature. It uses a DS18S20 1-wire sensor, which is directly attached to the i/o connector of the raspberry.

The temperature sensor connected to the 1-wire bus.

The temperature sensor connected to the 1-wire bus.

The measured temperature values can be accessed by a website served by a webserver running on the raspberry. You can see live values and historic values if the raspberry is online.

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HD44780 LC Display

Hardware

Many LC displays used today are based on a HD44780 (or compatible) controller. See AVR Thermometer for example. They can easily be interfaced to a microcontroller because of their simple parallel interface. They can display letters, numbers and a few special characters in 5 × 7 pixels. Additionally you can program 8 characters by yourself.

I/O Pins

The following is an overview of the i/o-pins of the display. The pin names are the ones often used in the displays datasheets.

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Eagle-Lib for AT90USB

Here you can download a device library for the PCB layout program Eagle from Cadsoft . It contains the device definition of the Atmel AVR microcontrollers AT90USB646, AT90USB647, AT90USB1286 and AT90USB1287 with USB interface.

The library is published under the terms of the LGPL. See http://www.gnu.org for more information about this license.

T6963-basiertes LC-Display

Hin und wieder werden recht günstig graphische LC-Displays von Restpostenanbietern verkauft. Ich habe eines von Pollin namens ‘DataVision DG12864-12′, Best.-Nr. 120 291 mit 128 × 64 Pixeln gekauft. Es eignet sich bestens, um es mit einem kleinen Microcontroller zu verbinden, denn es besitzt einen eingebauten Zeichengenerator, der die ersten 128 ASCII-Zeichen darstellen kann. Man kann entscheiden, ob man das Aussehen der Zeichen mit den Codes 0x7f bis 0xff oder sogar aller Zeichen selbst definieren möchte. Natürlich kann man aber auch Grafik anzeigen, also jeden Pixel einzeln setzen. Das Display-Modul verwendet den Chip T6963 von Toshiba.

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