Datasheet

ADuC7033
Rev. B | Page 80 of 140
TIMER1
Timer1 is a 32-bit general-purpose timer, count-down or count-
up, with a programmable prescaler. The prescaler source can be
the low power 32.768 kHz oscillator, the core clock, or from 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 48.83 ns
when operating at CD zero, the core is operating at 20.48 MHz,
and with a prescaler of 1 (ignoring the external GPIOs).
The counter can be formatted as a standard 32-bit value or as
hours:minutes:seconds:hundredths.
Timer1 has a capture register (T1CAP) that is triggered by a
selected IRQ source initial assertion. When triggered, the
current timer value is copied to T1CAP, and the timer continues
to run. This feature can be used to determine the assertion of an
event with increased accuracy.
The Timer1 interface consists of five MMRS.
• T1LD, T1VAL, and T1CAP are 32-bit registers and hold
32-bit unsigned integers. T1VAL and T1CAP are read only.
• T1CLRI is an 8-bit register. Writing any value to this
register clears the Timer1 interrupt.
• T1CON is the configuration MMR described in Table 54.
Timer1 features a postscaler allowing the user to count between
1 and 256 the number of Timer1 timeouts. To activate the post-
scaler, the user sets Bit 18 and writes the desired number to count
into Bits[31:24] of T1CON. When that number of timeouts is
reached, Timer1 can generate an interrupt if T1CON[18] is set.
Note that if the part is in a low power mode, and Timer1 is
clocked from the GPIO or low power oscillator source, Timer1
continues to operate.
Timer1 reloads the value from T1LD when Timer1 overflows.
Timer1 Load Registers
Name: T1LD
Address: 0xFFFF0320
Default Value: 0x00000000
Access: Read/write
Function: T1LD is a 32-bit register that holds the 32-bit
value that is loaded into the counter.
Timer1 Clear Register
Name: T1CLRI
Address: 0xFFFF032C
Access: Write only
Function: This 32-bit, write only MMR is written
(with any value) by user code to clear the
interrupt.
Timer1 Value Register
Name: T1VAL
Address: 0xFFFF0324
Default Value: 0xFFFFFFFF
Access: Read only
Function: T1VAL is a 32-bit register that holds the
current value of Timer1.
TIMER1
VALUE
LOW POWER
3
2.768kHz OSCILLATOR
CORE
CLOCK FREQUENCY
GPIO
GPIO
PRESCALER
1, 16, 256, OR 32768
TIMER1 IRQ
32-BIT
UP/DOWN COUNTER
8-BIT
POSTSCALER
32-BIT LOAD
CAPTURE
IRQ[31:0]
06847-031
Figure 35. Timer1 Block Diagram