AMD Elan SC520, User Manual, Page: 317 / 444

Élan™SC520 Microcontroller User’s Manual 17-1
CHAPTER
17
GENERAL-PURPOSE TIMERS
17.1 OVERVIEW
The general-purpose (GP) timers are intended for most generic timing or counting
applications, such as generating periodic interrupts and measuring or counting external
events.
Features of the general-purpose timers include:
■
Three 16-bit timers
■ Two-stage cascading of timers, to allow a maximum of two 32-bit timer/counter elements
■
Clock source from the system clock (33 MHz), an external pin, or a derived prescale
clock. The external pin and pre-scale clock are available for GP Timer 0 and GP Timer
1 only. The maximum clock is 33 MHz/4.
■ One external input pin for each timer for GP Timer 0 and GP Timer 1, used for external
event capture, pulse count, and counter reset/reload
■ One external output pin for GP Timer 0 and GP Timer 1
■
One interrupt output for each timer
■ Several modes of operation, including:
– Interrupt on terminal count
– Hardware retrigger mode
– Rate and square wave generation
– Continuous mode
17.2 BLOCK DIAGRAM
Figure 17-1 shows a block diagram of the general-purpose timers.
17.3 SYSTEM DESIGN
Table 17-1 shows the general-purpose timer signals shared with other interfaces. When
enabled, the multiplexed signals shown in Table 17-1 either disable or alter any other
function that uses the same pin.
Table 17-1 General-Purpose Timer Signals Shared with Other Interfaces
Default Signal Alternate Function Control Bit Register
TMROUT0 GPCS7 GPCS7_SEL Chip Select Pin Function Select (CSPFS)
register (MMCR offset C24h)
TMROUT1 GPCS6 GPCS6_SEL
TMRIN0 GPCS5 GPCS5_SEL
TMRIN1 GPCS4 GPCS4_SEL