Datasheet

ADuC7128/ADuC7129
Rev. 0 | Page 81 of 92
TIMER4—GENERAL-PURPOSE TIMER
TIMER4IRQ
CAPTURE
IRQ[31:0]
32-BIT LOAD
32-BIT
UP/DOWN COUNTER
TIMER1 VALUE
PRESCALER
1, 16, 256,
OR 32768
32.768kHz
OSCILLATOR
CORE CLOCK
FREQUENCY
GPIO
GPIO
06020-055
Figure 60. Timer4 Block Diagram
Timer4 is a 32-bit, general-purpose count down or count up
timer with a programmable prescalar. The prescalar source
can be the 32 kHz oscillator, the core clock, or one of two external
GPIOs. This source can be scaled by a factor of 1, 16, 256, or
32,768. This gives a minimum resolution of 42 ns when operating
at CD zero, the core is operating at 41.78 MHz, and with a prescalar
of 1 (ignoring external GPIO).
The counter can be formatted as a standard 32-bit value or as
hours:minutes:seconds:hundredths.
Timer4 has a capture register (T4CAP), which can be triggered
by a selected IRQ source initial assertion. Once triggered, the
current timer value is copied to T4CAP, and the timer keeps
running. This feature can be used to determine the assertion of
an event with increased accuracy.
The Timer4 interface consists of five MMRs.
Table 116. Timer4 Interface MMRs
Name Description
T4LD A 32-bit register. Holds 32-bit unsigned integers.
T4VAL
A 32-bit register. Holds 32-bit unsigned integers.
This register is read only.
T4CAP
A 32-bit register. Holds 32-bit unsigned integers.
This register is read only.
T4ICLR
An 8-bit register. Writing any value to this register
clears the Timer1 interrupt.
T4CON The configuration MMR (see Table 117).
Note that if the part is in a low power mode and Timer4 is clocked
from the GPIO or oscillator source, Timer4 continues to operate.
Timer4 reloads the value from T4LD either when Timer 4
overflows, or immediately when T4ICLR is written.
Timer4 Load Register
Name Address Default Value Access
T4LD 0xFFFF0380 0x00000 R/W
T4LD is a 32-bit register that holds the 32-bit value that is
loaded into the counter.
Timer4 Clear Register
Name Address Default Value Access
T4ICLR 0xFFFF038C 0x00 W
This 8-bit, write only MMR is written (with any value) by user
code to refresh (reload) Timer4.
Timer4 Value Register
Name Address Default Value Access
T4VAL 0xFFFF0384 0x0000 R
T4VAL is a 32-bit register that holds the current value of Timer4.
Timer4 Capture Register
Name Address Default Value Access
T4CAP 0xFFFF0390 0x00 R
This is a 32-bit register that holds the 32-bit value captured by
an enabled IRQ event.
Timer4 Control Register
Name Address Default Value Access
T4CON 0xFFFF0388 0x0000 R/W
This 32-bit MMR configures the mode of operation of Timer4.