{"product_id":"sh22-formaldehyde-hcho-sensor-module-uart","title":"SH22 Electrochemical Formaldehyde (CH2O) Sensor Module 0–5 PPM UART","description":"\u003ch2 id=\"accurate-formaldehyde-detection-for-air-quality-projects\" class=\"ng-star-inserted\"\u003e\u003cspan class=\"ng-star-inserted\"\u003eAccurate Formaldehyde Detection for Air Quality Projects\u003c\/span\u003e\u003c\/h2\u003e\n\u003cp class=\"ng-star-inserted\"\u003e\u003cspan class=\"ng-star-inserted\"\u003eThe SH22 sensor module uses an electrochemical sensing cell to measure indoor formaldehyde concentrations from 0 to 5 PPM with a resolution of ≤0.010 mg\/m³. Unlike basic semiconductor gas sensors that require complex analog calibration, the SH22 outputs pre-processed digital data directly over a 9600 bps UART serial interface. It supports both default 1-second active reporting (in ppb) and on-demand Q\u0026amp;A polling (returning both µg\/m³ and ppb), making integration straightforward on Arduino, ESP32, or STM32 boards.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch2 id=\"compact-3-3v-uart-integration-and-wiring\" class=\"ng-star-inserted\"\u003e\u003cspan class=\"ng-star-inserted\"\u003eCompact 3.3V UART Integration and Wiring\u003c\/span\u003e\u003c\/h2\u003e\n\u003cp class=\"ng-star-inserted\"\u003e\u003cspan class=\"ng-star-inserted\"\u003ePowered by 3.7V to 5.5V DC through its 7-pin 1.25mm connector, the SH22 communicates using 3.3V logic levels on its RXD (Pin 5) and TXD (Pin 6) lines. Its 23 x 25.5mm PCB includes four mounting holes and comes with a 7-pin ribbon cable for quick connection to custom carrier boards or microcontroller prototypes. Allow up to 3 minutes for sensor warm-up upon initial power-on, with typical response and recovery times within 60 seconds.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3 id=\"technician-tip\" class=\"ng-star-inserted\"\u003e\u003cspan class=\"ng-star-inserted\"\u003eTechnician Tip\u003c\/span\u003e\u003c\/h3\u003e\n\u003cp class=\"ng-star-inserted\"\u003e\u003cspan class=\"ng-star-inserted\"\u003ePay close attention to the 3.3V UART logic level and cross-sensitivity behavior before deploying the SH22. Our technicians at Sun Cheong advise using a bidirectional logic level shifter if connecting Pin 5 (RXD) to a 5V Arduino Uno, whereas 3.3V boards like ESP32 or Raspberry Pi can connect directly—even when powering Vin (Pin 4) at 5V. Also, avoid testing near alcohol wipes, hand sanitizers, or perfume, as 100 PPM of alcohol produces an equivalent reading of 40.6 PPM on this electrochemical cell; store the module in clean air (0–25°C) and avoid touching or puncturing the white top sensing membrane.\u003c\/span\u003e\u003c\/p\u003e","brand":"Sun Cheong Computer Company Limited","offers":[{"title":"Default Title","offer_id":68333860978839,"sku":"21PS002679","price":65.0,"currency_code":"HKD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0440\/4022\/4919\/files\/sh22-electrochemical-hcho-sensor-top-view.jpg?v=1794555758","url":"https:\/\/scccltd.com\/products\/sh22-formaldehyde-hcho-sensor-module-uart","provider":"Sun Cheong Computer Company Limited","version":"1.0","type":"link"}