4509 Datasheet, PDF (30/142 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4509 Group
(1) Timer control registers
• Timer control register PA
Register PA controls the count operation of prescaler. Set the con-
tents of this register through register A with the TPAA instruction.
• Timer control register W1
Register W1 controls the count operation and count source of
timer 1, and PWM1 function. Set the contents of this register
through register A with the TW1A instruction. The TAW1 instruction
can be used to transfer the contents of register W1 to register A.
• Timer control register W2
Register W2 controls the count operation and count source of
timer 2, and PWM2 function. Set the contents of this register
through register A with the TW2A instruction. The TAW2 instruction
can be used to transfer the contents of register W2 to register A.
• Timer control register W5
Register W5 controls the input count edge of CNTR0 pin, timer 1
count start synchronous circuit, timer 1 auto-stop circuit and P12/
CNTR0 pin function. Set the contents of this register through reg-
ister A with the TW5A instruction. The TAW5 instruction can be
used to transfer the contents of register W5 to register A.
• Timer control register W6
Register W6 controls the input count edge of CNTR1 pin, the INT
pin input count start synchronous circuit and CNTR1 pin output
auto-control circuit and the P11/CNTR1 pin function. Set the con-
tents of this register through register A with the TW6A instruction.
The TAW6 instruction can be used to transfer the contents of reg-
ister W6 to register A.
(2) Prescaler
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 and
2 count sources.
(3) Timer 1 (interrupt function)
Timer 1 is an 8-bit binary down counter with two timer 1 reload regis-
ters (R1L, R1H). Data can be set simultaneously in timer 1 and the
reload register R1L with the T1AB instruction. Data can be set in the
reload register R1H with the T1HAB instruction. The contents of re-
load register R1L set with the T1AB instruction can be set to timer 1
again with the T1R1L 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 T1HAB instruction to set data to reload register
R1H 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 R1L is n and a value set in re-
load register R1H is m, timer 1 divides the count source signal by n
+ 1 or m + 1 (n = 0 to 255, m = 0 to 255).
<Bit 3 of register W1 = “0” (PWM1 function invalid)>
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 inter-
rupt request flag (T1F) is set to “1,” new data is loaded from reload
register R1L, and count continues (auto-reload function).
<Bit 3 of register W1 = “1” (PWM1 function valid)>
Timer 1 generates the PWM1 signal of the “L” interval set as reload
register R1L, and the “H” interval set as reload register R1H. The
PWM1 signal generated by timer 1 is output from CNTR0 pin by set-
ting “1” to bit 3 of register W5.
After timer 1 control by INT pin is enabled by setting the bit 0 of reg-
ister I1 to “1”, INT pin input can be used as the start trigger for timer
1 count operation by setting the bit 1 of register W5 to “1”.
Also, in this time, the auto-stop function by timer 1 underflow can be
performed by setting the bit 2 of register W5 to “1.”
Rev.1.02 2006.12.22 page 30 of 140
REJ03B0147-0102