455A Datasheet, PDF (35/148 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

455A Group
Timer control register W5
W53 Not used
W52 Not used
W51
Timer 3 count source selection bits
W50
at reset : 00002
at power down : state retained
0 This bit has no function, but read/write is enabled.
1 This bit has no function, but read/write is enabled.
0 This bit has no function, but read/write is enabled.
1 This bit has no function, but read/write is enabled.
W51W52 Count source
00 XCIN input
01 ORCLK input
10 Low-speed on-chip oscillator
11 High-speed on-chip oscillator
R/W
TAW5/TW5A
(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
instruction.
• Timer control register W1
Register W1 controls the count operation and count source of
timer 1, and timer 1 count auto-stop circuit. 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, CNTR pin output, and extension function of PWM
signal “H” interval. 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 W3
Register W3 controls the count operation and count value of
timer 3. Set the contents of this register through register A with
the TW3A instruction. The TAW3 instruction can be used to
transfer the contents of register W3 to register A.
• Timer control register W4
Register W4 controls the input count edge of CNTR pin,
CNTR1 pin output auto-control circuit. Set the contents of this
register through register A with the TW4A instruction. The
TAW4 instruction can be used to transfer the contents of
register W4 to register A.
• Timer control register W5
Register W5 controls the count source of timer 3. Set the
contents of this register through register A with the TW5A
instruction. The TAW5A instruction can be used to transfer the
contents of register W5 to register A.
(2) Prescaler
Prescaler is an 8-bit binary down counter with the prescaler
reload register PRS. 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;
(1) set data in prescaler, and
(2) 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 can be selected 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.
Rev.1.01 Feb 15, 2008 Page 35 of 146
REJ03B0224-0101