xr16m698 Exar Corporation, xr16m698 Datasheet - Page 28

• Manufacturer Part Number: xr16m698
• Description: 1.62v To 3.63v High Performance Octal Uart With 32-byte Fifo
• Manufacturer: Exar Corporation

XR16M698
1.62V TO 3.63V HIGH PERFORMANCE OCTAL UART WITH 32-BYTE FIFO
TIMER OPERATION
The following paragraphs describe the operation of the 16-bit Timer/Counter. The following conventions will be
used in this discussion:
Timer Interrupt
In the one-shot mode, the Timer will issue an interrupt ’N’ clocks after the Timer is started. This is the time
when the Timer times-out in the one-shot mode. In the re-triggerable mode, the Timer will keep issuing an
interrupt every ’N’ clocks. This is shown in
triggereble mode) is ’N’ clocks. The Timer interrupt can be cleared by reading the TIMERCNTL register. The
TIMERCNTL will read a value of 0x01 when there is an interrupt and a 0x00 at all other times.
TIMERCNTL [7:4]
TIMERCNTL [3:0]
■
■
F
’N’ is the 16-bit value programmed in the TIMER MSB, LSB registers
‘N’ can take any value from 0x0002 to 0xFFFF.
IGURE
COMMANDS
TIMERCNTL
14. T
TIMERMSB and TIMERLSB
OSC. CLOCK
Reserved
These bits are used to invoke a series of commands that control the function of the Timer/Counter.
The commands 1011 to 1111 are reserved.
Upon power-up or reset, the default states are Timer interrupt disabled, Re-triggerable mode, Crystal
Oscillator as Timer clock source, and Timer stopped.
IMER
(16-bit Value)
TMRCK
/C
0001: Enable Timer Interrupt
0010: Disable Timer Interrupt (default)
0011: Select One-shot mode
0100: Select Re-triggerable mode (default)
0101: Select Internal Crystal Oscillator output as clock source for the Timer (default)
0110: Select External Clock source (through TMRCK pin) for the Timer
0111: Reserved
1000: Reserved
1001: Start Timer
1010: Stop Timer (default)
1011: Reset Timer
Clock Select
Start/Stop
Single shot/Re-triggerable
Timer Interrupt Enable/ Disable
OUNTER CIRCUIT
1
0
T
ABLE
11: TIMER C
Figure 15
Timer/Counter
16-Bit
28
, where the time between successive time-outs (in re-
ONTROL
C
Timer Interrupt
OMMANDS
1
0
Timer Interrupt
No Interrupt
REV. 1.0.0