Shiny server raspberry pi5/9/2023 ![]() The two SPI chip select (CS) pins go to GPIO 8 and 7 by default. The two devices can be wired to two separate ground pins on the GPIO. The thermocouple breakout board is run at 3.3v and the LED matrix is run at 5v. The two ends go to the two devices, while the single end goes to the Raspberry Pi. For these two pins, I made “Y” wires by soldering two wires to a single wire. Two of the Raspberry Pi GPIO pins are shared by the two devices (SPI clock and peripheral in). Writing two SPI devices gets a little convoluted. ![]() Click Yes when asked to enable the SPI interface, then reboot the Pi. Next, navigate through the config menus to Interfacing Options and then SPI. They’re bright, modular, and easy to control. I used an LED matrix driven by a MAX7219 breakout board. While it’s not necessary for the alarm system, having a display on the freezer that shows the current temperature is fun and can be a useful backup to the freezer’s own display. The Adafruit MAX31856 breakout board can drive several types of thermocouples if you go with a Type K, you can use the slightly cheaper MAX31855K breakout board. This is a little more accurate than the more common Type K, but a Type K would also work fine. For this project, I used an SLE Type T, which should have an accuracy of 0.5☌ or 0.4%, whichever is greater. Thermocouples come in lots of different types, but a Type T is commonly used for this application because of its ability to measure low temperatures and resist moisture. Thermocouple and displayĪt the heart of this system is a Type T thermocouple driven by an Adafruit MAX31856 thermocouple amplifier breakout board. I wrote about these steps in more detail, including connecting to the troublesome WiFi at University of Arizona, in this blog post. We’ll run it headless, so set up the Pi by installing Raspberry Pi OS on an SD card, enabling ssh, and configuring your network. I used a Raspberry Pi Zero W for this build, but any of the Raspberry Pi single-board computers should work fine.
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |