Ch341par.exe

ch341par.exe -w 0xAA Control register bit 0 = STROBE, active low.

Data: 0x00 Status: 0x79 Control: 0x0F Interpretation depends on your wiring. ch341par.exe -w 255 Now pins 2-9 go high (+5V / 3.3V depending on adapter). Example 3: Set data pins to binary pattern To set D7..D0 = 10101010 (0xAA):

ch341par.exe -s 0x0C ; 0x0C = 00001100 → INIT=1, others high Then pulse strobe low and back: ch341par.exe

ch341par.exe -s 0x0D ; low ch341par.exe -s 0x0C ; high -r returns status byte. Busy is bit 7 (value 0x80). Invert logic (busy low = printer busy).

1. What is ch341par.exe? ch341par.exe is a command-line utility for Windows (often included with CH341 series drivers ) that allows direct read/write access to the parallel port pins of a CH341-based USB-to-parallel adapter . ch341par

For serious projects, consider using the (also from WCH) which gives faster, programmatic access without shelling out to an EXE.

C:\Program Files (x86)\CH341\CH341PAR\ch341par.exe Example 3: Set data pins to binary pattern To set D7

First set all control pins high (inactive except INIT which is active high):

for _ in range(10): write_parallel(255) time.sleep(0.5) write_parallel(0) time.sleep(0.5) ch341par.exe is a simple but effective tool for low-speed parallel port control over USB. While limited compared to full CH341 DLL access, it’s perfect for quick testing, education, and basic automation scripts.

WCH CH341 Download Page (look for CH341PAR utility)