C8051F300/1/2/3/4/5
Rev. 2.9
21
1.6.
Programmable Counter Array
An on-chip Programmable Counter/Timer Array (PCA) is included in addition to the three 16-bit general
purpose counter/timers. The PCA consists of a dedicated 16-bit counter/timer time base with three pro-
grammable capture/compare modules. The PCA clock is derived from one of six sources: the system clock
divided by 12, the system clock divided by 4, Timer 0 overflows, an External Clock Input (ECI), the system
clock, or the external oscillator clock source divided by 8. The external clock source selection is useful for
real-time clock functionality, where the PCA is clocked by an external source while the internal oscillator
drives the system clock.
Each capture/compare module can be configured to operate in one of six modes: Edge-Triggered Capture,
Software Timer, High Speed Output, 8- or 16-bit Pulse Width Modulator, or Frequency Output. Additionally,
Capture/Compare Module 2 offers watchdog timer (WDT) capabilities. Following a system reset, Module 2
is configured and enabled in WDT mode. The PCA Capture/Compare Module I/O and External Clock Input
may be routed to Port I/O via the Digital Crossbar.
Figure 1.9. PCA Block Diagram
16-Bit Counter/Timer
CEX
1
EC
I
Digital Crossbar
CE
X2
CE
X0
Port I/O
Capture/Compare
Module 1
Capture/Compare
Module 0
Capture/Compare
Module 2
PCA
CLOCK
MUX
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
SYSCLK
External Clock/8
Summary of Contents for C8051F300
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