SX User’s Manual Rev. 3.1 165 © 2000 Scenix Semiconductor, Inc. All rights reserved. www.scenix.com Chapter 8 Multi-Function Timers 8.1     Introduction Some SX devices such as the SX48/52BD have a set of on-chip multi-function timers in addition to
the standard RTCC and Watchdog timers  found  in all  SX devices. The  SX48/52BD has  two such
multi-function  timers,  designated  T1  and  T2.  These  versatile,  programmable  timers  reduce  the
software burden on the CPU in real-time control applications such as PWM generation, motor control,
triac control, variable-brightness display control, sine wave generation, and data acquisition. Each timer consists of a 16-bit counter register supported by a 16-bit capture register and a 16-bit
comparison register. Each timer uses up to four I/O pins: one clocking input, two capture inputs, and
one timer output. The timer I/O pins are alternate functions of Port B pins for timer T1 and Port C pins
for Timer T2. Figure 8-1 is a block diagram showing the registers and I/O pins of one timer. The 16-bit free-running timer/counter register is initialized to 0000h upon reset and counts upward continuously. It is clocked
either by an external signal provided on an I/O pin or by the on-chip system clock divided by a value
selected by a 3-bit divide-by factor. Figure 8-1 Multi-Function Timer Block Diagram Ext. Clock Capture 1 Capture 2 3-bit Divide-by 16-Bit Free-Running 16-Bit Comparator 16-Bit Comparison Register R1 Timer/Counter 16-Bit Capture Register (1) MUX match Output Compare Interrupt System
Clock Capture Interrupt 16-Bit Comparison Register R2                            or
16-Bit Capture Register (2) Factor