$5 CH347 board is a USB 2.0 bridge to I2C, SPI, UART, JTAG, and GPIO

MuseLab USB-HS-Bridge is an inexpensive ($5) board based on WCH CH347 chip with a USB 2.0 Type-C interface that acts as a bridge for I2C, SPI, UART, and JTAG interfaces, as well as GPIOs.

It’s notably useful to debug and download bitstreams to FPGA development boards, but it can also be used to connect various peripherals such as I2C sensors, SPI flash devices, UART devices to basically any host with a spare USB 2.0 host port.

small CH347 development board

USB-HS-Bridge specifications:

  • Chip – WCH CH347 high-speed USB to UART, I2C, SPI and JTAG chip (See link to the datasheet for details)
  • USB – 1x USB 2.0 Type-C port with up to 480 Mbps data rate
  • I/Os – 2x 16-pin header with
    • 2x UART interfaces up to 9 Mbps baudrate
    • 1x I2C for EEPROM or sensors
    • 1x SPI master interface with 2 chip select signals to control up to 2x SPI slave devices. The SPI interface can operate up to 36MHz
    • 4-wire standard JTAG interface up to 60MHz
    • Some of the signals can also be reconfigured as GPIOs instead (CH347 offers up to 8x reconfigurable GPIOs depending on the mode used)
    • 5V, 3.3V, and GND signals
  • Misc – 2-way DIP switch for mode selection:
    • 00 – UART0 and UART1 enabled
    • 10 – UART1, I2C, and SPI (VCP = virtual COM port, driver required in Windows)
    • 01 – UART1, I2C, and SPI (HID – human interface device)
    • 11 – UART1 and JTAG enabled
  • Power Supply – 5V via USB port
  • Dimensions – 41 x 21 mm

USB HS BridgeThe CH347 is a fixed-function chip so there’s no firmware programming, but MuseLab still provided the PDF schematics, some instructions, the link to the Windows driver, and an SPI sample written in C language for Linux on Github.

CH347 use cases
Typical WCH CH347 system block diagram (RS232/RS485 require external chips)

USB-HS-Bridge CH347 board can be purchased for just $5 on Tindie or Aliexpress, although the latter may offer cheaper shipping depending on where you live.

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13 Replies to “$5 CH347 board is a USB 2.0 bridge to I2C, SPI, UART, JTAG, and GPIO”

  1. Does this chip/board also allow GPIO functionality. UART+GPIO would be nice, even if there are just one one or two GPIOs then.

    1. When I checked the datasheet yesterday, I could see 8 GPIOs shared with the UART signals, and it also appears the I2C pins can be used as GPIOs.

      1. Yes, I saw this. So in theory the GPIOs should even be accessible via the standard UART drivers via controlling DTR, CTS … I was hoping for pointers to articles online how to use the GPIOs practically with this chip/board.

  2. On this page http://www.wch-ic.com/downloads/CH347EVT_ZIP.html you can download a ZIP which contains (among other things) the “CH347 Application development manual”. Section 4.3 describes the API to get/set GPIO pins, but I suppose you must use their Windows USB driver for this to work. I’m not sure how this works at the USB level if you want to use it on a different platform.

    There’s also a USB configuration tool here: http://www.wch-ic.com/downloads/CH34xSerCfg_ZIP.html which may be relevant.

    1. Many Aliexpress links give me “Sorry, this item’s currently unavailable in your location” now. Am I the only one running into this?

      1. I can reproduce the error if I switch the country to Germany. I’m not sure why that is, as other EU countries seem fine.

  3. Hack the ch341a gpio Linux driver and add support for this chip?

    I had incomplete libusb gpio toggling for ch341a, curious to see if i could achevé more with this one.

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