CP2104 USB-to-Serial Breakout

CP2104 USB-to-Serial Breakout

This USB-to-serial adapter lets you easily connect a TTL serial device to a PC by acting as a virtual serial port. The board is a Micro-USB carrier for the Silicon Labs CP2104 USB-to-UART bridge that provides access to all of its control signal pins and GPIO pins.

The board is a great solution for connecting microcontroller projects and other logic-level serial devices to a personal computer. The tiny unit measures only 0.6″ × 0.95″ including its Micro-USB connector. It offers several options for accessing the data, control, and GPIO pins on the CP2104, all of which are made available on a 0.1″ spacing.

This board uses 3.45 V signal levels by default, but the signal pins can tolerate higher voltages, allowing the adapter to be used with 5 V systems that see 3.45 V as a logic high. The green LED on the SUSPEND line indicates an active USB connection when lit.

The adapter looks like a standard virtual serial port (COM port) to the computer’s operating system, which means it can be used with any software designed to work with a serial port (even a legacy RS-232 port). The CP2104 is a full-speed USB 2.0 device and allows baud rates of up to 2 Mbps. Drivers are available from Silicon Labs for Windows XP, Windows Vista, Windows 7, Windows 8, Linux, and Mac OS X.

Specifications

• Dimensions: 0.6″ × 0.95″ including connector
• USB standard: USB 2.0 (full speed)
• Connector: USB Micro-B
• Logic voltage level: 3.45 V (5 V tolerant)
• Supported baud rates: 300 bps to 2 Mbps
• Supply current: 25 mA

Using a different VIO

This carrier board connects the VIO pin of the CP2104 to VDD by default, setting its logic voltage level to the 3.45 V provided by the IC’s built-in voltage regulator. If you want to use a lower logic voltage, you can disconnect VIO from VDD by cutting the thin trace between the two pads of the surface-mount jumper shown to the right. You can then solder a thin wire to the exposed via labeled “VIO” and connect it to a separate voltage supply (as low as 1.8 V).

Documents

• CP2104 USB-to-UART bridge datasheet (224k pdf)
• CP2104 USB-to-serial adapter carrier schematic diagram (188k pdf)
• CP210x USB-to-UART bridge drivers
• Silicon Labs CP21xx USB-to-UART bridge product page