4507_M Datasheet, PDF (39/216 Pages) Renesas Technology Corp – 4-BIT CISC SINGLE-CHIP MICROCOMPUTER 4500 SERIES

4507 Group
HARDWARE
FUNCTION BLOCK OPERATIONS
Table 10 Timer control registers
Timer control register W1
at reset : 00002
at RAM back-up : 00002
R/W
W13 Prescaler control bit
W12 Prescaler dividing ratio selection bit
W11 Timer 1 control bit
W10 ^{Timer 1 count start synchronous circuit}
control bit
0
Stop (state initialized)
1
Operating
0
Instruction clock divided by 4
1
Instruction clock divided by 16
0
Stop (state retained)
1
Operating
0
Count start synchronous circuit not selected
1
Count start synchronous circuit selected
Timer control register W2
at reset : 00002
at RAM back-up : state retained
R/W
W23 Timer 2 control bit
0 Stop (state retained)
1 Operating
W22 ^{Timer 1 count auto-stop circuit selection}
bit (Note 2)
0 Count auto-stop circuit not selected
1 Count auto-stop circuit selected
W21
W21 W20
Count source
0 0 Timer 1 underflow signal
Timer 2 count source selection bits
W20
0 1 Prescaler output (ORCLK)
1 0 CNTR input
1 1 System clock
Timer control register W6
at reset : 00002
at RAM back-up : state retained
W63 Not used
W62 Not used
W61 CNTR output selection bit
W60 P12/CNTR function selection bit
0
This bit has no function, but read/write is enabled.
1
0
This bit has no function, but read/write is enabled.
1
0
Timer 1 underflow signal divided by 2 output
1
Timer 2 underflow signal divided by 2 output
0
P12(I/O)/CNTR input (Note 3)
1 P12 (input)/CNTR input/output (Note 3)
Notes 1: “R” represents read enabled, and “W” represents write enabled.
2: This function is valid only when the timer 1 count start synchronization circuit is selected.
3: CNTR input is valid only when CNTR input is selected as the timer 2 count source.
R/W
(1) Timer control registers
• Timer control register W1
Register W1 controls the count operation of timer 1, the selection
of count start synchronous circuit, and the frequency dividing ra-
tio and count operation of prescaler. 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 selection of timer 1 count auto-stop cir-
cuit, and the count operation and count source of timer 2. Set the
contents of this register through register A with the TW2A instruc-
tion. The TAW2 instruction can be used to transfer the contents
of register W2 to register A.
• Timer control register W6
Register W6 controls the P12/CNTR pin function and the selec-
tion of CNTR output. Set the contents of this register through
register A with the TW6A instruction. The TAW6 instruction can
be used to transfer the contents of register W6 to register A..
(2) Prescaler
Prescaler is a frequency divider. Its frequency dividing ratio can be
selected. The count source of prescaler is the instruction clock.
Use the bit 2 of register W1 to select the prescaler dividing ratio
and the bit 3 to start and stop its operation. Prescaler is initialized,
and the output signal (ORCLK) stops when the bit 3 of register W1
is cleared to “0.”
Rev.2.01 Feb 04, 2005
REJ09B0195-0201
1-27