{"id":24953,"date":"2022-03-15T08:00:35","date_gmt":"2022-03-14T23:00:35","guid":{"rendered":"https:\/\/www.souichi.club\/?p=24953"},"modified":"2022-03-19T17:15:14","modified_gmt":"2022-03-19T08:15:14","slug":"oled-deisplay","status":"publish","type":"post","link":"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/","title":{"rendered":"Display the results of CO2 concentration measurements on an OLED display"},"content":{"rendered":"\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_79_2 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Contents<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-69f0bc22f12fa\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #454e5c;color:#454e5c\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #454e5c;color:#454e5c\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-69f0bc22f12fa\"  aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#OLED_Display\" >OLED Display<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#Surface\" >Surface<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#backside\" >backside<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#About_CO2_Sensor\" >About CO2 Sensor<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#Wiring_Diagram\" >Wiring Diagram<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#Preliminary_Preparation\" >Preliminary Preparation<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#SSD1306_library\" >SSD1306 library<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#Sketch\" >Sketch<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#Supplemental_Explanation\" >Supplemental Explanation<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#Acquisition_of_CO2_concentration\" >Acquisition of CO2 concentration<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#Scrolling_display\" >Scrolling display<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.souichi.club\/en\/m5stack\/oled-deisplay\/#Execution_Result\" >Execution Result<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"OLED_Display\"><\/span>OLED Display<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>I got a 0.96 inch square OLED(Organic Light Emitting Diode) display and connected it to ESP32-WROOM-32 to display the measurement results of the CO2 sensor (MH-Z19C).<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><a class=\"r_image\" href=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-09.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-09.jpg?resize=480%2C411&#038;ssl=1\" alt=\"CO2 concentration on OLED display\" class=\"wp-image-24569\" width=\"480\" height=\"411\" srcset=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-09.jpg?w=1920&amp;ssl=1 1920w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-09.jpg?resize=768%2C657&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-09.jpg?resize=1536%2C1314&amp;ssl=1 1536w\" sizes=\"auto, (max-width: 480px) 100vw, 480px\" \/><\/a><\/figure>\n\n\n\n<p>The specifications of the OLED display are as follows<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Display size: 0.96 inches<\/li><li>Resolution: 128 x 64 px<\/li><li>Supply voltage: 3.3V to 5V *<\/li><li>Display controller: SSD1306<\/li><li>Interface: I2C<\/li><li>Display color: White<\/li><li>I2C address: 0x3C or 0x3D<\/li><\/ul>\n\n\n\n<p>This time, I tried connecting to both 3.3v and 5V, and both were displayed without any problem.<\/p>\n\n\n\n<p>When previously tested with an LCD (liquid crystal display), <a href=\"https:\/\/www.souichi.club\/en\/m5stack\/i2c-lcd\/\" target=\"_blank\" rel=\"noreferrer noopener\">the display darkened considerably when connected to 3.3V<\/a>, but this was not the case with this product.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Surface\"><\/span>Surface<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><a class=\"r_image\" href=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-05.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-05.jpg?resize=446%2C414&#038;ssl=1\" alt=\"OLED display Surface\" class=\"wp-image-24558\" width=\"446\" height=\"414\" srcset=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-05.jpg?w=1783&amp;ssl=1 1783w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-05.jpg?resize=768%2C713&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-05.jpg?resize=1536%2C1426&amp;ssl=1 1536w\" sizes=\"auto, (max-width: 446px) 100vw, 446px\" \/><\/a><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"backside\"><\/span>backside<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><a class=\"r_image\" href=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-04.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-04.jpg?resize=480%2C387&#038;ssl=1\" alt=\"Backside of OLED display\" class=\"wp-image-24557\" width=\"480\" height=\"387\" srcset=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-04.jpg?w=1920&amp;ssl=1 1920w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-04.jpg?resize=768%2C620&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-04.jpg?resize=1536%2C1239&amp;ssl=1 1536w\" sizes=\"auto, (max-width: 480px) 100vw, 480px\" \/><\/a><\/figure>\n\n\n\n<ul class=\"wp-block-list\"><li>Pins from left to right are SDA, SCL, VCC, and GND for I2C connection.<\/li><li>I2C address is shorted to 0x78 on the left side, which is 0x3C. If shorted to 0x7A on the opposite side, it becomes 0x3D.<\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"About_CO2_Sensor\"><\/span>About CO2 Sensor<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The MH-Z19C CO2 sensor was used to measure carbon dioxide.<\/p>\n\n\n\n<p>This sensor can output CO2 concentration to PWM or UART (serial).<\/p>\n\n\n\n<p>For details of MH-Z19C, <a href=\"https:\/\/www.souichi.club\/en\/m5stack\/co2sensor-mhz19c\/\" target=\"_blank\" rel=\"noreferrer noopener\">please refer to this article<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Wiring_Diagram\"><\/span>Wiring Diagram<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The wiring diagram is as follows<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><a class=\"r_image\" href=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-01.png?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-01.png?resize=960%2C540&#038;ssl=1\" alt=\"CO2 concentration on OLED display Wiring diagram\" class=\"wp-image-24964\" width=\"960\" height=\"540\" srcset=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-01.png?w=1920&amp;ssl=1 1920w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-01.png?resize=768%2C432&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-01.png?resize=1536%2C864&amp;ssl=1 1536w\" sizes=\"auto, (max-width: 960px) 100vw, 960px\" \/><\/a><\/figure>\n\n\n\n<p>The pin layout of the ESP32-WROOM-32 module used in this project is the same as that of the ESP32 DEVKIT V1 (30 pins).<\/p>\n\n\n\n<p>On the board, the bottom left pin is printed as VIN, but it is actually a 5V output pin.<\/p>\n\n\n\n<p>Please <a href=\"https:\/\/www.souichi.club\/en\/m5stack\/esp32-pin-layout\/#ESP32_DEVKIT_V1\" target=\"_blank\" rel=\"noreferrer noopener\">refer to this article<\/a> for the pin assignment of ESP32 DEVKIT V1.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><a class=\"r_image\" href=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-03.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-03.jpg?resize=476%2C285&#038;ssl=1\" alt=\"ESP-WROOM-32\" class=\"wp-image-24979\" width=\"476\" height=\"285\" srcset=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-03.jpg?w=1903&amp;ssl=1 1903w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-03.jpg?resize=768%2C459&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-03.jpg?resize=1536%2C919&amp;ssl=1 1536w\" sizes=\"auto, (max-width: 476px) 100vw, 476px\" \/><\/a><\/figure>\n\n\n\n<p>As mentioned above, the OLED display works fine at 3.3V.<\/p>\n\n\n\n<p>In the wiring diagram, it is powered from 5V, but there was no problem even if it was powered from 3V3 at the bottom right.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Preliminary_Preparation\"><\/span>Preliminary Preparation<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Arduino IDE (v1.8.19) on Windows 10 was used as the development environment.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"SSD1306_library\"><\/span>SSD1306 library<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>Since this OLED display uses the SSD1306 as its display controller, I anticipated that the Adafruit SSD1306 library would be available and installed it beforehand.<\/p>\n\n\n\n<p>I started the Arduino IDE, click to Tools&gt;Manage Libraries, started the Library Manager, searched for &#8220;SSD1306\u2033 and installed &#8220;Adafruit SSD1306&#8221; that showed up.<\/p>\n\n\n\n<p>Github <a href=\"https:\/\/github.com\/adafruit\/Adafruit_SSD1306\" target=\"_blank\" rel=\"noreferrer noopener\">is here<\/a>.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><a class=\"r_image\" href=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-02.png?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-02.png?resize=738%2C416&#038;ssl=1\" alt=\"Installing the Adafruit SSD1306 Library\" class=\"wp-image-24968\" width=\"738\" height=\"416\" srcset=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-02.png?w=984&amp;ssl=1 984w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-en-02.png?resize=768%2C432&amp;ssl=1 768w\" sizes=\"auto, (max-width: 738px) 100vw, 738px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Sketch\"><\/span>Sketch<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>A sketch of the CO2 concentration on an OLED display is shown below.<\/p>\n\n\n<pre class=\"line-numbers\"><code class=\"lang-cpp\">\/*\n * CO2 Sensor (MH-Z19C) readings are displayed on an OLED (Organic Light Emitting Diode) display\n * LCD:I2C\n *\/\n\n#include &lt;MHZ.h&gt; \/\/ CO2 Sensor\n#include &lt;Adafruit_SSD1306.h&gt; \/\/ OLED display\n\n#define SCREEN_WIDTH 128 \/\/ OLED display width, in pixels\n#define SCREEN_HEIGHT 64 \/\/ OLED display height, in pixels\n#define RX_PIN 16 \/\/ GPIO16\n#define TX_PIN 17 \/\/ GPIO17\n#define OLED_RESET 4 \/\/ Reset pin # (or -1 if sharing Arduino reset pin)\n#define SCREEN_ADDRESS 0x3C \/\/ I2C Address\n\nAdafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &amp;Wire, OLED_RESET);\nMHZ co2(RX_PIN, TX_PIN, MHZ19C); \/\/ Co2 Sensor\n\nvoid setup() {\n    Serial.begin(115200);\n    if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {\n        Serial.println(F(\"SSD1306 allocation failed\"));\n        for(;;); \/\/ Don't proceed, loop forever\n    }\n\n    display.display();\n    delay(2000);\n    display.clearDisplay(); \/\/ Buffer Clear\n\n    delay(100);\n    if (co2.isPreHeating()) {\n        display.setTextSize(1);\n        display.setTextColor(SSD1306_WHITE);\n        display.setCursor(0, 0);\n        display.println(F(\"Preheating\"));\n        display.display();\n        delay(100);\n        int x_pos = 0;\n        int y_pos = 10;\n\n        while (co2.isPreHeating()) {\n            delay(5000);\n            display.setCursor(x_pos, y_pos); \/\/ X Y\n            display.cp437(true); \/\/ Code Page 437 font(full 256 char)\n            display.write('.');\n            display.display();\n            if (x_pos &lt;= SCREEN_WIDTH){\n                x_pos +=10;\n            } else {\n                x_pos =0;\n                y_pos +=10;\n            }\n        }\n    }\n    \/\/ co2.setAutoCalibrate(true);\n}\n\nvoid loop() {\n    int ppm_uart = co2.readCO2UART();\n    Serial.println(\"Co2:\" + String(ppm_uart) + \" ppm\");\n    display.clearDisplay(); \/\/ Buffer Clear\n    display.setCursor(0, 0); \/\/ X Y\n    display.println(\"CO2:\" + String(ppm_uart) + \" ppm\");\n    int temperature = co2.getLastTemperature();\n    Serial.println(\"temp:\" + String(temperature) + \" c\");\n    display.setCursor(0, 20); \/\/ X Y\n    display.println(\"temp:\" + String(temperature) + \" c\");\n    display.display();\n    \/\/ display.startscrollleft(0x00, 0x0F);\n\n    delay(120000);\n}<\/code><\/pre>\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Supplemental_Explanation\"><\/span>Supplemental Explanation<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Acquisition_of_CO2_concentration\"><\/span>Acquisition of CO2 concentration<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p>Please <a href=\"https:\/\/www.souichi.club\/en\/m5stack\/co2sensor-mhz19c\/#Sketch_UART\" target=\"_blank\" rel=\"noreferrer noopener\">refer to the previous article<\/a> for the logic of obtaining Co2 concentration by MH-Z19C.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Scrolling_display\"><\/span>Scrolling display<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p>Commented out, but the display string scrolls to the left when line 69 is utilized.<\/p>\n\n\n<pre class=\"line-numbers\"><code class=\"lang-cpp\">    \/\/ display.startscrollleft(0x00, 0x0F);<\/code><\/pre>\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Execution_Result\"><\/span>Execution Result<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The image at runtime is shown below.<\/p>\n\n\n\n<p>CO2 concentration is displayed on the first line and temperature on the second line.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><a class=\"r_image\" href=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-06.jpg?ssl=1\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-06.jpg?resize=480%2C295&#038;ssl=1\" alt=\"CO2 concentration measurement results on OLED display\" class=\"wp-image-24560\" width=\"480\" height=\"295\" srcset=\"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-06.jpg?w=1920&amp;ssl=1 1920w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-06.jpg?resize=768%2C472&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-06.jpg?resize=1536%2C944&amp;ssl=1 1536w\" sizes=\"auto, (max-width: 480px) 100vw, 480px\" \/><\/a><\/figure>\n\n\n\n<p>This concludes this article.<\/p>\n\n\n<div class=\"postscript_balloon\">Finally.<\/div>\n\n\n<p>I hope this article will be useful to someone somewhere.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The measurement results of the CO2 sensor (MH-Z19C) were displayed on the display using ESP32. connection to the ESP32 module is I2C.<\/p>\n","protected":false},"author":5,"featured_media":24560,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_locale":"en_US","_original_post":"https:\/\/www.souichi.club\/?p=24551","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[238],"tags":[],"class_list":["post-24953","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-m5stack","en-US"],"aioseo_notices":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.souichi.club\/wp-content\/uploads\/oled-deisplay-06.jpg?fit=1920%2C1180&ssl=1","jetpack-related-posts":[],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/posts\/24953","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/comments?post=24953"}],"version-history":[{"count":13,"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/posts\/24953\/revisions"}],"predecessor-version":[{"id":24982,"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/posts\/24953\/revisions\/24982"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/media\/24560"}],"wp:attachment":[{"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/media?parent=24953"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/categories?post=24953"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.souichi.club\/wp-json\/wp\/v2\/tags?post=24953"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}