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orldwide Headquarters • 532 Race Street • San Jose, CA
95126-3432
T
elephone: 408.558.8500 • Fax: 408.558.8300 •
www
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Introduction
This Product Update lists precautions re
g
arding the
T
OUT
and
T
X
V
AL functions of the
Z8E000 and Z8E001 microcontrollers.
Related Documentation
Z8E000 Product Specifi
cation (DS0036)
Z8E001 Product Specifi
cation (DS0011)
T
OUT
Precaution
The
T
OUT
function uses the PTBOUT re
gister bit 1 directly by XORing it on each occur
-
rence of an interrupt.
The PWM reload is not based on the resulting v
alue.
The observ
ed functioning can be described as: follo
wing Reset, the
T
OUT
special function
is selected and the PWM is started.
The timer decrements from the v
alue in the counter
.
Upon the fi
rst time-out, the
T
OUT
pin fl
ips and the Lo
w-side reload v
alue is loaded into the
counter
.
The counter alternates from this point forw
ard, depending on which reload pair it
uses. If the PB1 pin is in the Lo
w output state when the
T
OUT
special function is enabled,
then the PWM is upside-do
wn from the be
ginning. If it is High, then the PWM is correct.
If softw
are modifi
es the PB1 output state, the pin changes states to refl
ect the softw
are-
dri
v
en v
alue, e
v
en though the pin is in the
T
OUT
special function mode. If the programmer
does not intentionally modify the bit and instead uses the Boolean operators on the
PTBOUT re
gister
, the timer fl
ips if the softw
are Read-Modify-Write operation happens to
f
all with a timer time-out in the middle. Because the timer and the CPU are running at dif
-
ferent di
visors of the master clock, this occurrence is not uncommon.
The softw
are write-
back o
v
errides the hardw
are change and the
T
OUT
pin does not change state as it should
ha
v
e. Because there is no feedback mechanism, this lack of state change causes the PWM
reload selection to be in
v
erted from the PWM output state.
T
x
V
AL
Precaution
There is a b
ug in the chip that causes the hardw
are write-back of the timers to corrupt the
softw
are
Write into the count v
alue re
gisters.
The timer v
alue re
gisters should not be writ
-
ten by softw
are unless the timer is stopped. Otherwise, the timer will not time-out during
the instruction
Product Update
Errata to
Z8E000/Z8E001 Silicon
UP003802-0703
ZiLOG W
orldwide Headquarters • 532 Race Street • San Jose, CA
95126-3432
T
elephone: 408.558.8500 • Fax: 408.558.8300 •
www
.zilog.com
Information Integrity
The information contained within this document has been v
erifi
ed according to the general princi
-
ples of electrical and mechanical engineering.
An
y applicable source code illustrated in the docu
-
ment w
as either written by an authorized ZiLOG emplo
yee or licensed consultant. Permission to
use these codes in an
y form besides the intended application, must be appro
v
ed through a license
agreement between both parties. ZiLOG will not be responsible for an
y code(s) used be
yond the
intended application. Contact your local ZiLOG Sales Of
fi
ce to obtain necessary license agree
-
ments.
Document Disclaimer
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gistered trademark of ZiLOG Inc. in the United States and in other countries.
All
other products and/or service names mentioned herein may be trademarks of the companies with
which the
y are associated.
©
2003
by ZiLOG, Inc.
All rights reserv
ed. Information in this publication concerning the de
vices,
applications, or technology described is intended to suggest possible uses and may be superseded.
ZiLOG, INC. DOES NO
T
ASSUME LIABILITY FOR OR PR
O
VIDE
A REPRESENT
A
TION OF
A
CCURA
CY OF
THE INFORMA
TION, DEVICES, OR
TECHNOLOGY DESCRIBED IN
THIS
DOCUMENT. ZiLOG ALSO DOES NOT ASSUME LIABILITY FOR INTELLECTUAL PROP-
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