# Arduino Temperature Indicator ## Description Temperature indicator using an Arduino Uno, a 16x2 I2C LCD, and a DHT22 temperature and humidity sensor, with minimal supporting components for pull-up and power stabilization. ## Project Details - **Owner:** devdutt12 - **Created:** 4/11/2026 - **Last Updated:** 4/11/2026 - **Visibility:** Public ## Key Components ### LCD1 — [WC1602A](https://www.flux.ai/jecstronic/wc1602a~vi0.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: WC1602A - Manufacturer Name: Wincom Tech - Datasheet URL: http://www.datasheet39.com/download.php?id=735838 - Implementation Details: Used in 4-bit mode through PCF8574 I2C expander. RS<-P0, E<-P1, D4<-P4, D5<-P5, D6<-P6, D7<-P7, RW tied low, A0/A1/A2 tied low for base I2C address. Contrast pin VO tied low as a minimal no-potentiometer default for schematic completeness. - Role Details: 16x2 character LCD display - Package: WC1602A - Part Type: Display Device - Role: Display **Pins:** - D0 [pin 7] - D1 [pin 8] - D2 [pin 9] - D3 [pin 10] - D4 [pin 11] - D5 [pin 12] - D6 [pin 13] - D7 [pin 14] - E [pin 6] - LED(-) [pin 16] - LED(+) [pin 15] - R/W [pin 5] - RS [pin 4] - VDD [pin 2] - VO [pin 3] - VSS [pin 1] ### U1 — [Arduino-UNO-R3](https://www.flux.ai/jecstronic/arduino-uno-r3~kf3.md) - Datasheet URL: https://media.digikey.com/pdf/Data%20Sheets/Arduino%20PDFs/A000066_Web.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Development Board - Manufacturer Part Number: Arduino-UNO-R3 - Role Details: Arduino Uno R3 board used as the primary controller and 5V source - Role: Main Controller - Manufacturer Name: Arduino - Package: Module **Pins:** - +3V3 [pin 4] - +5V [pin 5] - AREF [pin 30] - D0/RX [pin 15] - D1/TX [pin 16] - D10 [pin 25] - D11 [pin 26] - D12 [pin 27] - D13 [pin 28] - D14/A0 [pin 9] - D15/A1 [pin 10] - D16/A2 [pin 11] - D17/A3 [pin 12] - D18/A4 [pin 13] - D18/SDA [pin 31] - D19/A5 [pin 14] - D19/SCL [pin 32] - D2 [pin 17] - D3 [pin 18] - D4 [pin 19] - D5 [pin 20] - D6 [pin 21] - D7 [pin 22] - D8 [pin 23] - D9 [pin 24] - GND [pin 6] - GND [pin 7] - GND [pin 29] - IOREF [pin 2] - NC [pin 1] - RESET [pin 3] - VIN [pin 8] ### U2 — [DHT22-AM2302 Sensor Module](https://www.flux.ai/adrian95/dht22-am2302-sensor-module~8tv.md) - Role: Temperature and Humidity Sensor - Manufacturer Name: Adafruit Industries - Manufacturer Part Number: DHT22-AM2302 - Role Details: DHT22 single-wire digital sensor module - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://cdn-shop.adafruit.com/datasheets/Digital+humidity+and+temperature+sensor+AM2302.pdf - Implementation Details: DHT22 powered from 5V with DATA connected to Arduino D2 and external 10k pull-up to 5V. 100nF local decoupling provided on the 5V rail. - Part Type: Module - Package: Module **Pins:** - DATA [pin 2] - GND [pin 3] - VCC [pin 1] ### U3 — [PCF8574DWR](https://www.flux.ai/jecstronic/pcf8574dwr~mlh.md) - Manufacturer Name: Texas Instruments - Package: SOIC-16 - Manufacturer Part Number: PCF8574DWR - Role Details: PCF8574 I2C expander driving the HD44780-compatible LCD - Datasheet URL: https://rocelec.widen.net/view/pdf/zsmwgcsqj9/scps068j.pdf?t.download=true&u=5oefqw - License: https://creativecommons.org/licenses/by/4.0/ - Implementation Details: PCF8574 used as LCD I2C backpack equivalent. A0, A1, and A2 tied low. SDA and SCL connect to Arduino Uno I2C pins. P0/P1/P4/P5/P6/P7 drive LCD in 4-bit mode. - Part Type: Integrated Circuit - Role: I2C LCD Interface **Pins:** - ~INT~ [pin 13] - A0 [pin 1] - A1 [pin 2] - A2 [pin 3] - P0 [pin 4] - P1 [pin 5] - P2 [pin 6] - P3 [pin 7] - P4 [pin 9] - P5 [pin 10] - P6 [pin 11] - P7 [pin 12] - SCL [pin 14] - SDA [pin 15] - VDD [pin 16] - VSS [pin 8] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/devdutt12/arduino-temperature-indicator~37](https://www.flux.ai/devdutt12/arduino-temperature-indicator~37).* --- *Generated from [https://www.flux.ai/devdutt12/arduino-temperature-indicator~37](https://www.flux.ai/devdutt12/arduino-temperature-indicator~37)*