Datasheet

ADuC7033
Rev. B | Page 86 of 140
TIMER4 OR STI TIMER
Timer4 is a general-purpose, 16-bit, count up/count down
timer with a programmable prescaler. Timer4 can be clocked
from the core clock or the low power 32.768 kHz oscillator with
a prescaler of 1, 16, 256, or 32,768.
Timer4 has a capture register (T4CAP) that is triggered by a
selected IRQ source initial assertion. When triggered, the current
timer value is copied to T4CAP, and the timer continues running.
This feature can be used to determine the assertion of an event
with increased accuracy.
Timer4 is also used to drive the serial test interface (STI)
peripheral.
Timer4 interface consists of five MMRs.
• T4LD, T4VAL, and T4CAP are 16-bit registers and hold
16-bit unsigned integers. T4VAL and T4CAP are read only.
• T4CLRI is an 8-bit register. Writing any value to this
register clears the interrupt.
• T4CON is the configuration MMR described in Table 57.
Timer4 Load Register
Name: T4LD
Address: 0xFFFF0380
Default Value: 0x00000
Access: Read/write
Function: T4LD 16-bit register holds the 16-bit value
that is loaded into the counter.
Timer4 Clear Register
Name: T4CLRI
Address: 0xFFFF038C
Access: Write only
Function: This 8-bit, write only MMR is written (with
any value) by user code to clear the interrupt.
Timer4 Value Register
Name: T4VAL
Address: 0xFFFF0384
Default Value: 0xFFFF
Access: Read only
Function: T4VAL is a 16-bit register that holds the
current value of Timer4.
Timer4 Capture Register
Name: T4CAP
Address: 0xFFFF0390
Default Value: 0x0000
Access: Read only
Function: This is a 16-bit register that holds the 32-bit
value captured by an enabled IRQ event.
Timer4 Control Register
Name: T4CON
Address: 0xFFFF0388
Default Value: 0x00000000
Access: Read/write
Function: This 32-bit MMR configures the mode of
operation of Timer4.
PRESCALER
1, 16, 256, OR 32768
STI
TIMER4 IRQ
16-BIT
UP/DOWN COUNTER
LOW POWER
32.768kHz OSCILLATOR
CORE
CLOCK FREQUENCY
16-BIT LOAD
TIMER4
VALUE
CAPTURE
IRQ[31:0]
06847-034
Figure 38. Timer4 Block Diagram