340 lines
13 KiB
Markdown
340 lines
13 KiB
Markdown
# Temp. and Humidity Logger for the RPI4b
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This is a simple temperature and humidity logger for a Raspberry Pi 4B running
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FreeBSD 14. It is capable of taking temperature and humidity every 5
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seconds and storing them into a database. The measurements can then be viewed
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using either the integrated display, or, they can be exported to a USB drive.
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# Goals
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One of the most important goals for this project is that this device should be
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low maintenance. Therefore, you should not have to connect it to a computer or
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the network for years at a time. As this device has not yet been in service for
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more than a few weeks, this cannot yet be guaranteed, however, it has been
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designed to, at least in theory, be capable of this. It allows you to change the
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device's time, date, and timezone from the built in display, as well as allowing
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you to export data and clear the internal storage of collected data. Finally, it
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should be able to survive a full drive, however, as there are a lot of
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variables, it may not be able to.
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# Contents
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1. [Construction](#construction)
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2. [OS Preparation](#os-preparation)
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3. [Installation](#installation)
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4. [Configuration](#configuration)
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5. [Usage](#usage)
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# Construction
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The following is a general list of materials required:
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- 1x Raspberry Pi 4 Model B [^1]
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- 1x Breadboard (medium or large)
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- 4x Push button
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- 1x DHT11/DHT22 [^2]
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- 1x DS3231 (or other RTC)
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- 1x 16x2 HD44780U based LCD (such as a 1602 LCD, not I²C)
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- 1x N-channel MOSFET (optional, for turning off the screen)
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- 1x Schottky diode (optional, for turning off the screen)
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- 1x 1kΩ resistor [^3]
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- 2x 10kΩ potentiometers (optional, for display brightness and contrast control)
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[^1]: Other versions and models will very likely work (such as the Pi 3B), the
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wiring will just need to be adjusted.
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[^2]: Any temperature and humidity sensor for which a FreeBSD kernel module
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exists will work. You can even use separate sensors for each!
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[^3]: If your DHT11/DHT22 is mounted on a carrier board with only three
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terminals, it likely already has this resistor. When in doubt, check the
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data sheet.
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The following is one possible way to assemble the device. It should be noted,
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however, that all of the pins are configurable. Thus, the following design
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should be modified depending on the exact make and model of the parts being
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used.
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If an I²C device will be used (such as the DS3231 or an I²C sensor), care must
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be taken that the data lines are connected to GPIO pins 2 and 3 (physical pins 3
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and 5). If they are not, the configuration files provided in this repository
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will need to be updated to reflect the new I²C bus location. If multiple I²C
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devices are used, multiple busses will need to be created. For more information
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about I²C on FreeBSD see the following man pages: [iic(4)][1], [iicbus(4)][2],
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and [fdt(4)][3].
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[1]: https://man.freebsd.org/cgi/man.cgi?query=iic&apropos=0&sektion=4&manpath=FreeBSD+14.0-RELEASE+and+Ports
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[2]: https://man.freebsd.org/cgi/man.cgi?query=iicbus&apropos=0&sektion=4&manpath=FreeBSD+14.0-RELEASE+and+Ports
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[3]: https://man.freebsd.org/cgi/man.cgi?query=fdt&apropos=0&sektion=4&manpath=FreeBSD+14.0-RELEASE+and+Ports
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Some images of a fully assembled and working unit follow:
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# OS Preparation
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This software was designed and tested on a system running FreeBSD 14.0. However,
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it should work on systems running FreeBSD 13 as well as on systems running
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future versions of FreeBSD. The FreeBSD installation process is very well
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documented in [The FreeBSD Handbook][4]. For convinience, the general procedure
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is also provided below. If any issues arise or you have any questions, be
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consult the handbook.
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[4]: https://docs.freebsd.org/en/books/handbook/
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First, download the latest image for the Raspberry Pi [here][5]. It is also a
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good idea to pick up the checksum file. Once done you should have two files with
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names similar to `FreeBSD-14.0-RELEASE-arm64-aarch64-RPI.img.xz` and
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`CHECKSUM.SHA256-FreeBSD-14.0-RELEASE-arm64-aarch64-RPI`. To verify the
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downloaded files, open a terminal and execute the following commands (use sha512
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if you downloaded the sha512 checksum file):
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[5]: https://www.freebsd.org/where/
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- GNU/Linux and FreeBSD:
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```sh
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sha256sum -c CHECKSUM.SHA256-FreeBSD-14.0-RELEASE-arm64-aarch64-RPI
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```
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- OpenBSD:
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```sh
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sha256 -c CHECKSUM.SHA256-FreeBSD-14.0-RELEASE-arm64-aarch64-RPI
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```
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For other operating systems, please consult the relevant documentation.
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Because device numbering is not persistent across boots, the export feature of
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this software does not allow a specific device to be excluded from the
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list. This may in the feature be rectified by an update, but for now, it is
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recommend to install the OS to a microSD card. Most Raspberry Pis come with a
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small USB device that can be used to write to microSD cards, as well as the
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microSD card itself. If not, you can find both online very cheaply. Once you
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have connected your device find it's device file using a tool like `fdisk` or
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`geom`. Then execute the following commands as root to write the image to the
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microSD card:
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```sh
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unxz FreeBSD-14.0-RELEASE-arm64-aarch64-RPI.img.xz
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cp FreeBSD-14.0-RELEASE-arm64-aarch64-RPI.img /path/to/device
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sync
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```
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If you are not comfortable with performing this operation on the terminal,
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another option is to use software such as [balenaEtcher][6].
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[6]: https://etcher.balena.io/
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Once this process is done (which may take a while), insert the microSD card into
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the Raspberry Pi, attach a keyboard and monitor, and plug the Pi in to turn it
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on.
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# Installation
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Once the system has booted and you see the login prompt, enter `root` as the
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username and leave the password blank. You should now see a shell prompt. The first
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thing to do is to configure the temperature sensor and the RTC. To do the
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former, *append* the following to the end of the `/boot/loader.conf` file:
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```conf
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# Load the DHT11/DHT22 kernel module
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gpioths_load="YES"
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# The GPIO bus that manages the pins that the sensor is connected to
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hint.gpioths.0.at=gpiobus0
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# This number should have only the bit set for the position corresponding to the
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# GPIO pin number that the sensor is connected to. For example:
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# 2097152 -> 1000000000000000000000 -> pin 21 (bit 22)
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# 1 -> 1 -> pin 0 (bit 1)
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# 2 -> 10 -> pin 1 (bit 2)
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hint.gpioths.0.pins=2097152
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# Load the DS3231 kernel module
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ds3231_load="YES"
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# The I2C bus the controls the pins the sensor is connected to
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hint.ds3231.0.at=iicbus0
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# The *8 BIT* address of the sensor. The following is the default for a DS3231
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# addr = 0xd0
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hint.ds3231.0.addr=208
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```
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The FreeBSD base system comes with the text editor `vi`. For information about
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how to use it, execute `man vi` or see [vi(1)][7].
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[7]: https://man.freebsd.org/cgi/man.cgi?query=vi&manpath=FreeBSD+14.0-RELEASE+and+Ports
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The next step is to enable I²C for the DS3231. Once again, *append* the
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following to the end of the `[all]` section of the `/boot/msdos/config.txt`
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file:
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```conf
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# Set the initial state of pins GPIO 2 and 3. Change this if you use different pins.
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gpio=2,3=a0
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# Load the overlay for an the DS3231 I2C real-time clock
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dtoverlay=i2c-rtc,ds3231
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```
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For example, the `/boot/msdos/config.txt` file on my Raspberry Pi 4B looks like
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this:
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```conf
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[all]
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arm_64bit=1
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dtparam=audio=on,i2c_arm=on,spi=on
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dtoverlay=mmc
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dtoverlay=disable-bt
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device_tree_address=0x4000
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kernel=u-boot.bin
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gpio=2,3=a0
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dtoverlay=i2c-rtc,ds3231
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[pi4]
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hdmi_safe=1
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armstub=armstub8-gic.bin
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enable_uart=1
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```
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If you want, you can also change the `root` password at this point:
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```sh
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passwd
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```
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After doing this, reboot the system. Once done, execute the following commands:
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```sh
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sysctl dev.ds3231.0.temperature dev.gpioths.0.temperature
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```
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If you get a warning about an unknown oid, it means that the sensor is not
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installed or configured correctly. The following commands can help in debugging
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the problem. For example, if the battery in the DS3231 has gone bad, the above
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command will show no error, however, the below command will print a warning
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message.
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```sh
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dmesg | grep -i ds3231 # for ds3231 debugging
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dmesg | grep -i gpioths # for temperature sensor debugging
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```
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It should be noted that FreeBSD does not currently support wireless on the
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Raspberry Pi 4 at the time of writing. Thus, you will need to use a wired
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connection (or consult the [handbook][4] for information about other ways to get
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packages).
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Once the sensors are detected and we have internet, we can install the
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dependencies for this software. Execute the following command to bootstrap the
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binary package manager [pkg(7)][8] and install sqlite3 and curl.
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[8]: https://man.freebsd.org/cgi/man.cgi?query=pkg&manpath=FreeBSD+14.0-RELEASE+and+Ports
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```sh
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pkg install sqlite3 curl
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```
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When prompted to install `pkg`, type `y` and then press enter.
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We can now download the source of this software:
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```sh
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cd /tmp
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curl -O "https://git.zander.im/Zander671/rpi4b-temp-humidity/archive/main.tar.gz"
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tar xf main.tar.gz
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cd rpi4b-temp-humidity
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```
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If you do plan on connecting the device to the internet long term (remember to
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arrange for it to be updated!!!), you can enable the ntpd and ntpdate services
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to sync with an NTP server.
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```sh
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service ntpd enable # sync periodically
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service ntpdate enable # sync on boot
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```
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At this point, take a moment to edit the `config.mk` file to to change any
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default options. These can also be changed after installation by editing
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`/usr/local/etc/rpi4b-temp-humidity/config.conf`.
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Once you have configured everything to your liking, execute the following
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command to build and install the software.
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```sh
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make install
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```
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# Configuration
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The final step is to configure the software via the
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`/usr/local/etc/rpi4b-temp-humidity/config.conf` file. Once you have done this
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to your liking, execute the following command to enable the software on boot:
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```sh
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# Optional, set an alternate config file path
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sysrc rpi4b_temp_humidity_config_file="/path/to/your/config/file"
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service rpi4b-temp-humidity enable
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```
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The following command line flags are supported:
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- `-h`: print a simple help message, then exit
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- `-v`: enable more verbose output
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- `-s`: exit immediately if an error is found in the config file
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- `-f`: specify a different config file path
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These can also be modified via the following [rc.conf(5)][9] variables (or via
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the [sysrc(8)][10] command).
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- `rpi4b_temp_humidity_config_file`: same as `-f`
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- `rpi4b_temp_humidity_strict_config`: same as `-s`
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- `rpi4b_temp_humidity_verbose`: same as `-v`
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- `rpi4b_temp_humidity_log_file`: file to write output to, set to empty to
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discard output
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[9]: https://man.freebsd.org/cgi/man.cgi?query=rc.conf&manpath=FreeBSD+14.0-RELEASE+and+Ports
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[10]: https://man.freebsd.org/cgi/man.cgi?query=sysrc&manpath=FreeBSD+14.0-RELEASE+and+Ports
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# Usage
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The buttons from closest to the display to farthest are: select, back, up, and
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down. When the device first turns on, the stats screen will be shown. This screen
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displays the current temperature, humidity, and time. Pressing the back button
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will take you to the main menu. The following is a short description of each screen:
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- `Current stats` - the current time, temperature, and humidity
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- `Stats by` - show stats by a specific period (e.g. hour, day, week). Press
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the select button while on a stats screen to cycle what is displayed. Use up
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and down while on a stats screen to got to the next or previous period.
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- `Data points` - view individual data points. Press up or down to go to the next
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or previous data point.
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- `Average range` - show stats between two times. This has the same controls as
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the "Stats by" screen above.
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- `Export` - export data to a plugged in USB drive. Only file-systems detected
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by [fstyp(8)][11] are supported. If a drive with an unsupported file-system,
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or no file-system, is selected, you will be prompted to format it as
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FAT32. Exports can be done in both sqlite3 and CSV format. The temperature is
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in deci-Kelvin (1/10 of a kelvin) and the humidity is an integer percent
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(ex. 53% would just be 53). The time is seconds since January 1, 1970 UTC.
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- `Blank display` - turn off the display. Press any button to cancel. You must
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have specified a "bl_pin" in the config file.
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- `Power options` - re-initialize the program, shutdown or reboot the device
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- `View date/time` - show the current date and time down to the second
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- `Set date/time` - set the current date and time. The time entered is in local
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time.
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- `Set timezone` - set the timezone. The prompts will guide you through creating a
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timezone as described in [tzset(3)][12]. Another, possibly easier to
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understand description can be found in the corresponding Linux man page
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[tzset(3)][13].
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- `Clear data` - **DELETE ALL DATA** on the device. When the operation is complete,
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the database will be empty. **NO BACKUP IS MADE** so be careful.
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As a final note on the usage of the "Stats by", "Data points", and "Average
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range" screens, pressing the up and down buttons to move across different DST
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stats can cause some weird-looking behavior. If this causes you trouble, simply
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back out of the stats screen and enter back in from a different start date. As
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this is the expected behavior of the various sqlite3 and libc date and time
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functions, it will not be fixed (because it's not broken).
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[11]: https://man.freebsd.org/cgi/man.cgi?query=fstyp&manpath=FreeBSD+14.0-RELEASE+and+Ports
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[12]: https://man.freebsd.org/cgi/man.cgi?query=tzset&manpath=FreeBSD+14.0-RELEASE+and+Ports
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[13]: https://man.archlinux.org/man/tzset.3
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