Submitted by Neil Davey:

patch #4539: Ability to control the bit clock (usleep) delay
for ppi interface
* bitbang.c: Implement bitbang_delay() and its calibration.
* bitbang.h: Declare bitbang_delay().
* main.c: Add the ispdelay option (-i).
* pgm.h (struct programmer_t): Add the ispdelay parameter.
* par.c: Add calls to bitbang_delay() when requested.
* serbb_posix.c: (Ditto.)
* serbb_win32.c: (Ditto.)
* avrdude.1: Document the new -i option.
* doc/avrdude.texi: (Ditto.)


git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk/avrdude@610 81a1dc3b-b13d-400b-aceb-764788c761c2

avrdude.1

@@ -19,7 +19,7 @@
 .\"
 .\" $Id$
 .\"
-.Dd DATE July 19, 2006
+.Dd DATE August 16, 2006
 .Os
 .Dt AVRDUDE 1
 .Sh NAME
@@ -38,6 +38,7 @@
 .Op \&, Ns Ar exitspec
 .Oc
 .Op Fl F
+.Op Fl i Ar delay
 .Op Fl n
 .Op Fl P Ar port
 .Op Fl q
@@ -330,6 +331,24 @@ reasonable before continuing.  Since it can happen from time to time
 that a device has a broken (erased or overwritten) device signature
 but is otherwise operating normally, this options is provided to
 override the check.
+.It Fl i Ar delay
+For bitbang-type programmers, delay for approximately
+.Ar delay
+microseconds between each bit state change.
+If the host system is very fast, or the target runs off a slow clock
+(like a 32 kHz crystal, or the 128 kHz internal RC oscillator), this
+can become necessary to satisfy the requirement that the ISP clock
+frequency must not be higher than 1/4 of the CPU clock frequency.
+This is implemented as a spin-loop delay to allow even for very
+short delays.
+On Unix-style operating systems, the spin loop is initially calibrated
+against a system timer, so the number of microseconds might be rather
+realistic, assuming a constant system load while
+.Nm
+is running.
+On Win32 operating systems, a preconfigured number of cycles per
+microsecond is assumed that might be off a bit for very fast or very
+slow machines.
 .It Fl n
 No-write - disables actually writing data to the MCU (useful for debugging
 .Nm avrdude