From: Steven Baltakatei Sandoval Date: Tue, 27 Oct 2020 18:50:37 +0000 (+0000) Subject: feat(exec/temperature):Add poll py script, update README X-Git-Url: https://zdv2.bktei.com/gitweb/EVA-2020-02.git/commitdiff_plain/c3dcde6195bbcaec4ad805526be55f983e6ba784?ds=inline feat(exec/temperature):Add poll py script, update README Add links to wiring instructions --- diff --git a/doc/temperature/README.org b/doc/temperature/README.org index f48a44c..64b0760 100644 --- a/doc/temperature/README.org +++ b/doc/temperature/README.org @@ -5,7 +5,7 @@ ** About This document was created by Steven Baltakatei Sandoval on ~2020-10-24T23:37Z~ under a [[https://creativecommons.org/licenses/by-sa/4.0/][Creative Commons BY-SA 4.0 license]]. It was -updated by Steven Baltakatei Sandoval on ~2020-10-24T23:59Z~ +updated by Steven Baltakatei Sandoval on ~2020-10-27T18:50Z~ ** Narrative The ~ninfacyzga-01~ device may log temperature readings from @@ -23,12 +23,28 @@ Several types of temperature sensors may be equipped: - The Raspberry Pi Zero W's internal temperature CPU sensors Whatever the source, an associated ~python~ script should report the -temperature in the form of JSON data sent to the script's standard -output ("stdout") stream. +temperature and associated metadata within a JSON value outputted to +the script's "stdout" stream and formatted using the following +standards: + +- [[https://www.json.org/json-en.html][JSON]] (JavaScript Object Notation): A data-interchange format. + +- [[https://jsonlines.org/][JSON Lines]] : A method of formatting JSON values so they may be + streamed using newline characters as separators. + +- [[https://www.w3.org/TR/json-ld/][JSON-LD]] (JSON Linked Data): A messaging format capable of encoding + RDF data (ex: RDF triples) in a JSON value. + +- [[https://www.w3.org/TR/vocab-ssn/][SSN]] (Semantic Sensor Network Ontology): A namespace for building RDF + graphs describing relationships between various characteristics of a + sensing system (ex: Which sensor made the observation? What kind of + observation was made? Which station was the sensor a part of? Where + was the station? When was an observation made?). An example + application of SSN ontology to NOAA weather data can be found [[https://github.com/anhlt18vn/Semantic2019][here]]. In turn, this "stdout" is then piped into the ~bklog~ which takes care -of packaging, encrypting, and appending the JSON data to a timestamped -~tar~ file. +of packaging, encrypting, and appending the stream of JSON lines to a +timestamped ~tar~ file. ~cron~ is used to call a single script which performs all of the above actions at regular time intervals. @@ -41,18 +57,106 @@ actions at regular time intervals. *** Software - [[https://www.raspberrypi.org/downloads/raspberry-pi-os/][Raspberry Pi OS]] : A GNU/Linux operating system derived from Debian 10. This procedure was developed with version ~August 2020~. +*** Output +**** Simple +Temperature readings may be recorded into a comma-delimited format: + +#+BEGIN_EXAMPLE +20201027T182039+0000,1603822839,18.37500 +20201027T182041+0000,1603822841,18.43700 +20201027T182043+0000,1603822843,18.43700 +20201027T182045+0000,1603822845,18.43700 +#+END_EXAMPLE + +**** JSON-LD log +A typical temperature reading will be formatted thus: + +(TODO: Insert example output following JSON-LD, SSN standards) + +#+BEGIN_EXAMPLE +{ + "@context": { + "sosa": "http://www.w3.org/ns/sosa/", + "rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#", + "rdfs": "http://www.w3.org/2000/01/rdf-schema#", + "xsd": "http://www.w3.org/2001/XMLSchema#" + "ssn": "http://www.w3.org/ns/ssn/" + } + "temperature" +} +#+END_EXAMPLE + + ** Operating Procedures *** Initial Startup **** Perform initial setup. See [[file:../setup/README.org][Main Setup]] procedure. **** Install Hardware for temperature logging +***** DS18B20 1-Wire wiring +The DS18B20 temperature sensor must be connected to the Raspberry Pi's +GPIO pins through a circuit assembly that contains a "pull-up" 4.7KΩ +resistor. A circuit diagram may be found [[https://electrosome.com/ds18b20-sensor-raspberry-pi-python/][here]]. The data lead should be +connected to GPIO pin 4 (physical pin number 7; see [[https://pinout.xyz/][ref]]). Using a +different GPIO pin will require a slightly different 1-Wire +configuration. + +**** Install Software for temperature logging +***** DS18B20 1-Wire programming +The DS18B20 temperature sensor output may be polled by a Python script +via the Raspberry Pi's "1-Wire" communications protocol. + +****** Enabling 1-Wire support +1-Wire support at GPIO pin 4 is enabled by adding the following lines +to ~/boot/config.txt~: + +: # Enable 1-Wire at GPIO 4 (DS18B20 temperature probe) +: dtoverlay=w1-gpio,gpiopin=4 + +****** Testing DS18B20 1-Wire availability + +The temperature sensor output may be manually polled by running the +following commands: + +: sudo modprobe w1-gpio +: sudo modprobe w1-therm +: cd /sys/bus/w1/devices/ + +There should be a directory with a name resembling +~28-3c01b556f672~. Enter it and read the ~w1_slave~ file. + +: cd 28-3c01b556f672 +: cat w1_slave + +An example of such output will resemble: + +#+BEGIN_EXAMPLE +2a 01 55 05 7f a5 a5 66 76 : crc=76 YES +2a 01 55 05 7f a5 a5 66 76 t=18625 +#+END_EXAMPLE + +The ~YES~ in the first line indicates the 1-Wire protocol is +functioning. The ~t=18625~ indicates that the DS18B20 sensor is +detecting the temperature to be ~18.625°C~. + +****** Sample script to automatically poll DS18B20 sensor + +A sample python script for automatically outputting a stream of +temperature readings via stdout is explained [[https://pimylifeup.com/raspberry-pi-temperature-sensor/][here]] (along with wiring +instructions) and found [[https://github.com/pimylifeup/temperature_sensor][here]]. + +***** Install temperature logging scripts +Several scripts in this repository should be installed to the local +user's executable directory at ~$HOME/.local/bin~. + +Cron jobs should be configured (via ~$ crontab -e~) to call these +scripts automatically. -**** Install Software for temperature loggin +: [TODO fill me] ***** Install packages via ~apt~ Run the following command to install the required packages. -: $ sudo apt install [fill me] +: $ sudo apt install [TODO: fill me] *** Normal Startup *** Normal Operation diff --git a/exec/temperature/DS18B20..temp_poll.py b/exec/temperature/DS18B20..temp_poll.py new file mode 100644 index 0000000..21a727b --- /dev/null +++ b/exec/temperature/DS18B20..temp_poll.py @@ -0,0 +1,40 @@ +#!/usr/bin/env python3 + +import os +import glob +import time +from time import strftime + +os.system('modprobe w1-gpio') +os.system('modprobe w1-therm') + +base_dir = '/sys/bus/w1/devices/' +device_folder = glob.glob(base_dir + '28*')[0] +device_file = device_folder + '/w1_slave' + +def read_temp_raw(): + f = open(device_file, 'r') + lines = f.readlines() + f.close() + return lines + +def read_temp(): + lines = read_temp_raw() + while lines[0].strip()[-3:] != 'YES': + time.sleep(0.2) + lines = read_temp_raw() + equals_pos = lines[1].find('t=') + if equals_pos != -1: + temp_string = lines[1][equals_pos+2:] + temp_c = float(temp_string) / 1000.0 + temp_f = temp_c * 9.0 / 5.0 + 32.0 + temp_c_2dec = f"{temp_c:.5f}" # https://stackoverflow.com/a/15263885/10850071 + #return temp_c, temp_f + return temp_c_2dec + +while True: + nowTimeIso8601 = strftime("%Y%m%dT%H%M%S%z") + nowTimeUE = strftime("%s") + nowTemp = read_temp() + print(str(nowTimeIso8601) + ',' + str(nowTimeUE) + ',' + str(nowTemp)) + time.sleep(1)