CH347 programmer on Windows 11: the driver each USB interface takes, what 55DA to 55DE mean, and the software that actually reads it

Last checked: 23 October 2026.

The CH347 is WCH’s 480 Mbit/s successor to the CH341A: SPI at up to 60 MHz, I2C, two UARTs, JTAG, and on the CH347F also SWD and a 1.8 V I/O rail. The catch on Windows 11 is that it is not one device. Every CH347 board shows up as two or more USB interfaces, each wanting a different driver, and the product ID (55DA to 55DE) tells you which mode the board was wired into. Get the mode wrong and no programmer software will ever list it.

This guide gives you the drivers, the mode table, the software that actually talks to the chip, and the five failures people hit, each tied to a real report.

Install, in this order

1. Unplug the programmer. Run CH343SER.EXE → Install. This covers the serial interface the chip always exposes.
2. Run CH341PAR.EXE → Install. This is the one AsProgrammer, NeoProgrammer-style tools and WCH’s own library talk to. Its INF covers 1A86:55DB, 55DD and 55DE under the name USB HighSpeed-SPI/I2C… CH347T / CH347F (read out of CH341WDM.INF in the CH341A guide).
3. Plug the board in and open Device Manager. In mode 1 you should see two entries: a COM port named USB-HiSpeed-SERIAL-A CH347 under Ports, and the CH347T SPI/I2C device under Interface. Those strings are the DeviceDesc values in CH343SER.INF 1.9.2024.09 and CH341WDM.INF.
4. Unzip AsProgrammer, start it, open Hardware and pick CH347, not CH341A. Then Detect.
5. If the Hardware menu finds nothing, do not reinstall drivers yet. Check the product ID first, with the table below.

The mode table: what each product ID means on Windows

Per the CH347 datasheet V1.4 (§5.2), the CH347T samples two pins at reset, DTR1 (pin 10) and RTS1 (pin 13), and the result sets both the function set and the default PID. The CH347F has no mode pins: it is always the 5-in-1 55DE and the driver switches functions. Device Manager → the device → Details → Hardware Ids shows the PID.

Two IDs that get mislabelled in open-source rule files: OpenOCD’s driver also probes 1A86:55E7 as “other chip”, and probe-rs’s udev rules list 55E8 as “the third product id WCH’s tools use”. In CH343SER.INF, 55E7 is the CH339 (USB-HiSpeed-SERIAL-A CH339) and 55E8 is the four-port CH9114. Neither is a CH347; if you see them, you have a different chip.

Which software actually drives a CH347

The five failures, in the order to check them

1. AsProgrammer’s Hardware menu shows CH347 but Detect finds nothing, and Device Manager shows two COM ports. The board is in mode 0 (PID 55DA): two UARTs, no SPI. Retail programmer boards strap DTR1 high and RTS1 low for mode 1; dev-board style modules have a jumper or DIP for the two pins. Change it with the board unplugged; the chip reads the pins only at reset.

2. Chip ID reads 0x000000, 0xFFFFFF, or changes between reads. Clock too high for the wiring. flashrom defaults to 15 MHz, and One Transistor’s CH347T software test reports a 32 MB part reading in seconds at 15 MHz with writes taking about six minutes. With a SOIC-8 clip and 20 cm leads, start at 15 MHz or lower; use 30 and 60 MHz only on a socket. Then check the usual: clip orientation, pin 8 power, and the clip contact problems.

3. A 1.8 V flash (W25Q…JW, MX25U…, most laptop and phone parts) detects wrongly or not at all. The CH347T is 3.3 V only (datasheet §2.1: “Support only 3.3V power supply voltage”), so it needs a 1.8 V level adapter exactly like the CH341A. The CH347F is the one with a VIO pin: 1.8 to 3.3 V, and 1.2 V on lot 5 ≥ 4. If your board says CH347F, set its voltage selector before clipping on.

4. JTAG works on one board and not another, or OpenOCD warns about the chip version. The silicon has firmware revisions and they matter. WCH’s issue tracker records a chip that answered JTAG with twice the expected bits (issue 13: “two versions of the chip, 1.4x and 2.4x. In later one jtag works, but i2c in mode 3 stops working”) and a December 2022 CH347T that hung in the FPGA tool until replaced by a newer part marked “x041” (issue 32). OpenOCD’s driver reads bcdDevice and prints what it knows: below 2.41 JTAG is bit-banged only; 2.41 has “very weird clock timing”; 4.41 limits SWD to 1 MHz and drives SWDIO high for 392 ns after ACK (add a series resistor); 5.44 allows 5 MHz SWD. The OpenOCD manual says it outright: “WCH CH347T chips have rather poor performance with respect to the USB HS connection. Upgrade firmware to the latest version!” How to upgrade is not documented publicly; issue 55 asking for it was open as of September 2026.

5. flashrom says “CH347 not found” although AsProgrammer works. On Windows, flashrom uses libusb and needs WinUSB bound to the SPI interface (interface 2 on the T, 4 on the F), while AsProgrammer needs WCH’s CH341PAR on that same interface. They cannot coexist. Zadig to flashrom, then to go back: Device Manager → the WinUSB device → Uninstall with “delete the driver” ticked, replug, and CH341PAR takes over again. flashrom also refuses mode 2 (HID) by design and mode 3 (no SPI endpoint).

Linux and macOS, briefly

The UART half binds to WCH’s ch343 driver on Linux (the CH9102 / CH343 guide hosts it with a checksum); its ID table carries 55DA, 55DB, 55DD, 55DE and 55E7, interface 0 only. The SPI/I2C/JTAG half has no kernel driver: flashrom and OpenOCD open it through libusb, so you need a udev rule. OpenOCD’s 60-openocd.rules already lists 55DD and 55DE; probe-rs’s rules add 55E8. WCH’s own ch341par_linux SDK instead creates /dev/ch34x_pis* and works, per its README, with “ch347t mode1/mode3, ch347f”. For I2C EEPROMs with WCH’s official Windows tool, One Transistor found the clock fixed at 800 kHz and had “no luck reading I2C EEPROMs”; AsProgrammer handled them.

FAQ

CH341A or CH347: is the speed difference real? Yes. The CH341A is full-speed USB (12 Mbit/s); the CH347 is high-speed (480 Mbit/s) with SPI selectable up to 60 MHz. The practical ceiling is your wiring, not the chip, which is why 15 MHz is the sane default.

Do I need Zadig for a CH347? Only for flashrom or OpenOCD on Windows. AsProgrammer and WCH’s library want CH341PAR. Zadig and CH341PAR fight over the same interface.

My board is labelled “CH347T V1.1”. Is that the firmware version? No, that is the carrier board revision. The chip revision is bcdDevice in the USB descriptor: the REV_ part of the Hardware Ids line in Device Manager (REV_0241 = 2.41), or lsusb -v on Linux. OpenOCD prints it at start.

Related guides

• CH341A programmer and AsProgrammer: driver, software and chip list
• CH341A 3.3 V mod: how far over spec the 5 V really is
• flashrom on Windows
• USB VID/PID lookup for bench tools
• SOIC-8 test clips: why reads fail
• CMSIS-DAP, DAPLink and WCH-LinkE on Windows 11

Sources

• WCH, CH347 datasheet V1.4 (26 Jun 2025): §2 features, §5.2 working-mode table and default PIDs
• WCH, CH341PAR.EXE 2.6 and CH343SER.EXE 2.2 download pages
• CH343SER.INF, DriverVer 1.9.2024.09 (inside the hosted dregmod zip): device strings per PID
• therealdreg/asprogrammer-dregmod: README, v5 release notes with per-file SHA-256
• nofeletru/UsbAsp-flash releases: 2.1.0 to 2.1.2
• flashrom programmers/ch347_spi.c: device table, speed list, interface numbers, HID TODO
• OpenOCD src/jtag/drivers/ch347.c and doc/openocd.texi: PIDs, chip-version warnings (commit 99cb670, Feb 2025)
• 60-openocd.rules and 69-probe-rs.rules
• WCHSoftGroup/ch347 (issues 13, 32, 55) and ch341par_linux README
• bigbigmdm/IMSProg README
• One Transistor: CH347T programmer schematic (Sep 2024) and drivers and software for Windows (Nov 2024, updated Oct 2025)