This serial LCD module gets power and data through one wire
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I found this interesting post on EDN by Benabadji Noureddine about driving an HD44780-based LCD module serially through one wire. It receives the display data as well as power supply through the same single wire connected to the UART TX pin of the host microcontroller. The LCD module itself uses a PIC12F508 microcontroller that receives the serial data from the host MCU and transfers it to the LCD in 4-bit mode. The clever trick in this design is during idle condition, the UART TX output from the host MCU remains high, which is used to supply power to the PIC12F508 MCU and the LCD. During the data transmission, a simple capacitor and diode circuit is used to continue providing the stable DC power to the LCD and PIC MCU.
1-wire serial LCD
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