The CH340G is a popular, low-cost USB-to-Serial UART bridge chip. It is widely used to connect microcontrollers or industrial hardware to a computer's USB port.An important technical distinction exists regarding its communication voltage levels: the CH340G natively outputs TTL (0V to 3.3V/5V) serial signals, not true RS-232 signals (-15V to +15V).The Critical Difference: TTL vs. True RS-232When buying or using a "CH340G USB to RS232" module, double-check your device's voltage requirements:
- USB to TTL (UART) Modules: Most cheap CH340G modules labeled "RS232" are actually TTL converters. They break out pins like VCC, GND, TXD, and RXD. These operate safely at 3.3V or 5V and are meant for microcontrollers, router unbricking, or programming boards like Arduinos.
- True RS-232 Modules: If you are connecting to industrial equipment, old modems, or PLC machinery with a standard 9-pin DB9 connector, you need true RS-232 voltage levels. For a CH340G to achieve this, the board must include a level-shifting transistor chip (such as the MAX232) to boost the signal. Connecting a pure TTL adapter to a high-voltage industrial RS-232 device can permanently damage the CH340G chip.
Key Specifications
- USB Interface: USB 2.0 full-speed compliant.
- Baud Rates: Supports data transfer rates from 50 bps up to 2 Mbps.
- Hardware Flow Control: Includes standard modem signals (RTS, CTS, DTR, DSR).
- Clocking: Requires an external 12 MHz crystal oscillator on the PCB circuit to function.
Drivers & OS SupportThe CH340G requires specific device drivers to establish a Virtual COM Port (VCP) on your computer.
- Windows: Usually requires manual driver installation via the official CH341SER installer. Once installed, it shows up in Device Manager as "USB-SERIAL CH340 (COMx)".
- macOS & Linux: Modern Linux distributions have the driver built directly into the kernel. Modern macOS editions typically support it out of the box.
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Drop Shipping:- I do not support drop-shippers, unless you contact beforehand and get agreement that I can ship without logos/ packaging/etc.- If you buy an item, and leave a note demanding specific action - I will cancel the order if the order, especially if it says "please package in a new box, don't use any tape, please ship today, please deliver to FedEx tonight and send a picture of receipt of dropoff".- If you simply want the order shipped with no invoice, and no logos/branding, that is totally fine- I ship using bright ORANGE tape with BLUE shipping labels.
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