4552 Datasheet, PDF (64/145 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4552 Group
LIST OF PRECAUTIONS
➀Noise and latch-up prevention
Connect a capacitor on the following condition to prevent noise
and latch-up;
• connect a bypass capacitor (approx. 0.1 µF) between pins VDD
and VSS at the shortest distance,
• equalize its wiring in width and length, and
• use relatively thick wire.
In the One Time PROM version, CNVSS pin is also used as VPP
pin. Accordingly, when using this pin, connect this pin to VSS
through a resistor about 5 kΩ (connect this resistor to CNVSS/
VPP pin as close as possible).
In addtion, the MCU may be replaced with mask ROM version
without the need to remove the resistor from the circuit and with-
out any adverse effect on operation.
➁Register initial values 1
The initial value of the following registers are undefined after sys-
tem is released from reset. After system is released from reset,
set initial values.
• Register Z (2 bits)
• Register D (3 bits)
• Register E (8 bits)
➂Register initial values 2
The initial value of the following registers are undefined at RAM back-
up. After system is returned from RAM back-up, set initial values.
• Register Z (2 bits)
• Register X (4 bits)
• Register Y (4 bits)
• Register D (3 bits)
• Register E (8 bits)
➅Timer count source
Stop timer 1, 2 and LC counting to change its count source.
➆Reading the count value
Stop timer 1 or 2 counting and then execute the data read in-
struction (TAB1, TAB2) to read its data.
➇Writing to the timer
Stop timer 1, 2 or LC counting and then execute the data write in-
struction (T1AB, T2AB, TLCA) to write its data.
➈Writing to reload register R1, R2H
When writing data to reload register R1, reload register R2H
while timer 1 or timer 2 is operating, avoid a timing when timer 1
or timer 2 underflows.
10 Timer 2
Avoid a timing when timer 2 underflows to stop timer 2 at PWM
output function used.
When “H” interval extension function of the PWM signal is set to
be “valid”, set “1” or more to reload register R2H.
11 Timer 3
Stop timer 3 counting to change its count source.
12 _{Timer input/output pin}
Set the port C output latch to “0” to output the PWM signal from
C/CNTR pin.
➃ Stack registers (SKS)
Stack registers (SKs) are eight identical registers, so that subrou-
tines can be nested up to 8 levels. However, one of stack
registers is used respectively when using an interrupt service
routine and when executing a table reference instruction. Accord-
ingly, be careful not to over the stack when performing these
operations together.
➄ Prescaler
Stop counting and then execute the TABPS instruction to read
from prescaler data.
Stop counting and then execute the TPSAB instruction to set
prescaler data.
Rev.3.02 Dec 22, 2006 page 64 of 142
REJ03B0023-0302