4571 Datasheet, PDF (27/126 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4571 Group
The 4571 Group timer consists of the following circuits.
• Prescaler : 8-bit programmable timer
• Timer 1 : 8-bit programmable timer
• Timer 2 : 8-bit programmable timer
• Timer 3 : 8-bit programmable timer
• Watchdog timer: 16-bit fixed frequency timer
(Timers 1, 2 and 3 have the interrupt function, respectively)
Prescaler, timer 1, timer 2 and timer 3 can be controlled with the
timer control registers PA, W1, W2, W3 and W5. The watchdog
timer is a free counter which is not controlled with the control
register.
Each function is described below.
Table 16 Function related timers
Circuit
Structure
Prescaler 8-bit programmable
binary down counter
Timer 1
Timer 2
8-bit programmable
binary down counter
(link to INT0 input)
(carrier wave output auto-
control function)
8-bit programmable
binary down counter
Timer 3
8-bit programmable
binary down counter
(with carrier wave
generation function)
Watchdog 16-bit fixed dividing
timer
frequency
Count source
• Instruction clock (INSTCK)
• Instruction clock divided by 4
(INSTCK/4)
• PWM signal (PWMOUT)
• Prescaler output (ORCLK)
• CNTR0 input (CNTR0IN)
• System clock (STCK)
• PWM signal (PWMOUT)
• Timer 1 underflow (T1UDF)
• Prescaler output (ORCLK)
• System clock (STCK)
• XIN input
• Prescaler output divided by 2
(ORCLK/2)
• Instruction clock (INSTCK)
Frequency
dividing ratio
Use of output signal
1 to 256
• Timer 1 count source
• Timer 2 count source
• Timer 3 count source
1 to 256
• Timer 2 count source
• CNTR0 output
• Carrier wave output auto-
control
• Timer 1 interrupt
1 to 256 • CNTR0 output
• Timer 2 interrupt
Control
register
PA
W1
W5
W2
W5
1 to 256 • Timer 1 count source
W1
• Timer 2 count source
W3
• CNTR1 output
W5
• Timer 3 interrupt
65536 • System reset (counting twice)
-
• Decision of flag WDF1
Rev.1.02 May 25, 2007 Page 27 of 124
REJ03B0179-0102