in libcpu/powerpc/mpc860/clock/clock.c:InstallClock() the reload value for
the PIT is defined as:
pit_value = (BSP_Configuration.microseconds_per_tick *
Cpu_table.clicks_per_usec) - 1 ;
What exactly is a tick, and what is a click?
My confusion stems from the fact, that Jay defines clicks_per_usec to 1
which is correct for his configuration, where a 4MHz clock is predivided
by 4 and then fed to the PIT. So I assume a "click" is just the period of
the PIT input frequency.
However, our HW config seems to have 32.768 kHz crystal input for PIT.
Mandatory division by 4 means 8.196kHz (122usec) at the PIT.
I think, the above assignment should read:
pit_value = (BSP_Configuration.microseconds_per_tick /
Cpu_table.clicks_per_usec) - 1;
where I can define Cpu_table.clicks_per_usec in bspstart.c to 122
(clicks_per_usec). That would lead to a PIT reload value of
10000/122 - 1 = 81 to reach a 10ms "tick" period.
in libcpu/powerpc/mpc860/clock/clock.c:InstallClock() the reload value for
the PIT is defined as:
pit_value = (BSP_Configuration.microseconds_per_tick *
Cpu_table.clicks_per_usec) - 1 ;
What exactly is a tick, and what is a click?
My confusion stems from the fact, that Jay defines clicks_per_usec to 1
which is correct for his configuration, where a 4MHz clock is predivided
by 4 and then fed to the PIT. So I assume a "click" is just the period of
the PIT input frequency.
However, our HW config seems to have 32.768 kHz crystal input for PIT.
Mandatory division by 4 means 8.196kHz (122usec) at the PIT.
I think, the above assignment should read:
pit_value = (BSP_Configuration.microseconds_per_tick /
Cpu_table.clicks_per_usec) - 1;
where I can define Cpu_table.clicks_per_usec in bspstart.c to 122
(clicks_per_usec). That would lead to a PIT reload value of
10000/122 - 1 = 81 to reach a 10ms "tick" period.
a BSP for the TS-1325 embedded PC from Technologic Systems
(http://www.t-systems.com) and patches to enable software
floating-point emulation for x86 targets.
I have made test with the Dec21140 driver and it appears that all
works fine even if the cache is enabled for the memory space in
which the incoming and outcoming Ethernet frames are stored.
I have had #ifdef to "comment" the code. If you want to disable
cache, you only have to #define the name. It could be mandatory
for some BSPs.
University of British Columbia. The BSP is for:
Yes, this is the "entry model" of a series of boards from Technologic
Systems. Costs <$200 I believe. They have a WWW page at www.t-systems.com.
I am letting them know about the availability of this BSP too.
Joel Sherrill