Openocd With Parport Investigation
December 6, 2016
Parallel ports aren’t a common port anymore and so, don’t have much support. A Windows driver giveio.sys was previously used on 32-bit Windows to support parallel port jtag device use with OpenOCD. There isn’t a 64-bit version of giveio.sys. OpenOCD can’t communicate with parallel port on a 64-bit windows OS using giveio.sys and results with an error: Error: missing privileges for direct i/o.
There are some alternative 64-bit parallel port drivers that can be used with 64-bit windows OS. The driver I went with is InpOutx64 found here: inpout. There’s a couple steps to make this work
- Installing the driver and including the inpoutx64.dll in openocd/bin folder
- Modify OpenOCD code to use inpoutx64 instead of giveio
OpenOCD could be modified for 64-bit windows; this guide will show the steps I took to get my parallel port JTAG wiggler to work with 64-bit Windows 10.
The Steps
64-bit parallel port driver
download inpout32 Extract and run the driver installer aptly named InstallDriver.exe in the InpOutBinaries_1501\Win32 sub folder
Modify the OpenOCD source
I can’t take much credit here as I found that someone had already suggested a patch to use inpoutx64. Original post here and patch: message board, for whatever reason, that patch wasn’t applied to the OpenOCD project.
So, here are the source files of my applied modifications: OpenOCDModFiles. The specific source file for enabling parallel port functionality is src/jtag/driver/parport.c
Building
Follow the build procedure at gnuarmoeclipse copy/replace the parport.c before building with /build-openocd.sh --Win64
Setup inpoutx64.dll
Go back to the extracted InpOutBinaries_1501 folder and copy the inpoutx64.dll and place it in the openocd/bin folder (same folder as the openocd.exe)
Testing OpenOCD
open a cmd shell, cd to the location of the OpenOCD.exe and run openocd -f interface/parport.cfg -f target/"target processor" in this case -f target/lpc2138.cfg
Now OpenOCD should be running
