4552 Datasheet, PDF (33/145 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4552 Group
(1) Timer control registers
• Timer control register PA
Register PA controls the count operation of prescaler. Set the
contents of this register through register A with the TPAA instruc-
tion.
• Timer control register W1
Register W1 controls the selection of timer 1 count auto-stop cir-
cuit, and the count operation and count source of timer 1. Set the
contents of this register through register A with the TW1A instruc-
tion. The TAW1 instruction can be used to transfer the contents
of register W1 to register A.
• Timer control register W2
Register W2 controls the CNTR output, the expansion of “H” in-
terval of PWM output, and the count operation and count source
of timer 2. Set the contents of this register through register A with
the TW2A instruction. The TAW2 instruction can be used to trans-
fer the contents of register W2 to register A.
• Timer control register W3
Register W3 controls the count operation and count source of
timer 3. Set the contents of this register through register A with
the TW5A instruction. The TAW3 instruction can be used to trans-
fer the contents of register W3 to register A.
• Timer control register W4
Register W4 controls the operation and count source of timer LC,
the selection of CNTR output auto-control circuit and the count
edge of CNTR input. Set the contents of this register through reg-
ister A with the TW4A instruction. The TAW4 instruction can be
used to transfer the contents of register W4 to register A..
(2) Prescaler (interrupt function)
Prescaler is an 8-bit binary down counter with the prescaler reload
register RPS. Data can be set simultaneously in prescaler and the
reload register RPS with the TPSAB instruction. Data can be read
from reload register RPS with the TABPS instruction.
Stop counting and then execute the TPSAB or TABPS instruction
to read or set prescaler data.
Prescaler starts counting after the following process;
➀ set data in prescaler, and
➁ set the bit 0 of register PA to “1.”
When a value set in reload register RPS is n, prescaler divides the
count source signal by n + 1 (n = 0 to 255).
Count source for prescaler is the instruction clock (INSTCK).
Once count is started, when prescaler underflows (the next count
pulse is input after the contents of prescaler becomes “0”), new
data is loaded from reload register RPS, and count continues
(auto-reload function).
The output signal (ORCLK) of prescaler can be used for timer 1, 2,
and 3 count sources.
(3) Timer 1 (interrupt function)
Timer 1 is an 8-bit binary down counter with the timer 1 reload reg-
ister (R1). Data can be set simultaneously in timer 1 and the reload
register (R1) with the T1AB instruction. Data can be written to re-
load register (R1) with the TR1AB instruction. Data can be read
from timer 1 with the TAB1 instruction.
Stop counting and then execute the T1AB or TAB1 instruction to
read or set timer 1 data.
When executing the TR1AB instruction to set data to reload regis-
ter R1 while timer 1 is operating, avoid a timing when timer 1
underflows.
Timer 1 starts counting after the following process;
➀ set data in timer 1
➁ set count source by bits 0 and 1 of register W1, and
➂ set the bit 2 of register W1 to “1.”
When a value set in reload register R1 is n, timer 1 divides the
count source signal by n + 1 (n = 0 to 255).
Once count is started, when timer 1 underflows (the next count
pulse is input after the contents of timer 1 becomes “0”), the timer
1 interrupt request flag (T1F) is set to “1,” new data is loaded from
reload register R1, and count continues (auto-reload function).
INT pin input can be used as the start trigger for timer 1 count op-
eration by setting the bit 0 of register I1 to “1.”
Also, in this time, the auto-stop function by timer 1 underflow can
be performed by setting the bit 3 of register W1 to “1.”
Rev.3.02 Dec 22, 2006 page 33 of 142
REJ03B0023-0302