really support multiple parallel ports

[usb-driver] / README

diff --git a/README b/README
index 87fe8be309867cd7d781ef56d3be8c0573367a18..597b1b2313596ef03ba478bf7011ca686f320d06 100644 (file)
--- a/README
+++ b/README
@@ -3,7 +3,7 @@ userspace which are required by XILINX impact to access the Platform cable USB
 and Parallel Cable III.
 With this library it is possible to access the cables without loading a
 proprietary kernel module which breaks with every new kernel release. It uses
-the functions provided by the libusb userspace library for USB access and
+the functionality provided by the libusb userspace library for USB access and
 the kernel interface at /dev/parport0 for parallel port access instead and
 should work on every kernel version which is supported by libusb and supports
 ppdev. It was written against impact from ISE Webpack 9.1SP1 and tested with
@@ -26,6 +26,9 @@ $ export LD_PRELOAD=/path/to/libusb-driver.so  (for sh shells)
 $ setenv LD_PRELOAD /path/to/libusb-driver.so  (for csh shells)
 $ impact
 
+The source for this library can be found at:
+http://cvs.zerfleddert.de/cgi-bin/viewcvs.cgi/usb-driver/
+
 
 Notes for the USB cable
 =======================
@@ -66,3 +69,18 @@ ppdev
 
 
 To use the device as an ordinary user, put the user in the group 'lp'
+
+
+Parallel Cable IV is currently only supported in 'compatibility mode', as no
+attempt to configure the ECP registers is done by this library.
+
+
+If you get "Programming failed" or "DONE did not go high" when programming
+through the parallel cable with Impact 9.1, make sure to have the option "Use
+HIGHZ instead of BYPASS" enabled in Edit -> Preferences -> iMPACT Configuration
+Preferences.
+If you are using batch mode, add the following line to your cmd file:
+setPreference -pref UseHighz:TRUE
+(This problem also occurs on windows and when using the real windrvr in linux and
+is solved with the same workaround. Impact 8.2 is working fine with the same
+boards and designs)