C8051F326 Datasheet, PDF (129/140 Pages) List of Unclassifed Manufacturers – Full Speed USB, 16 kB Flash MCU Family

C8051F326/7
14. Timers
Each MCU includes two 16-bit timers compatible with those found in the standard 8051. These timers can
be used to measure time intervals and generate periodic interrupt requests. Timer 0 and Timer 1 are nearly
identical and have four primary modes of operation.
Timer 0 and Timer 1 Modes:
13-bit timer
16-bit timer
8-bit timer with auto-reload
Two 8-bit timers (Timer 0 only)
Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits (T1M-
T0M) and the Clock Scale bits (SCA1-SCA0). The Clock Scale bits define a pre-scaled clock from which
Timer 0 and/or Timer 1 may be clocked (See Figure 14.3 for pre-scaled clock selection). Timer 0/1 may
then be configured to use this pre-scaled clock signal or the system clock.
Timers 0 and 1 have a gate mode which allows the timer to run only when an external interrupt is active
(/INT0 for Timer 0 and /INT1 for Timer 1. This mode facilitates pulse width measurements on input on P0.2
(Timer 0) and Low Frequency oscillator calibration when used with Timer 1.
14.1. Timer 0 and Timer 1 Operating Modes
Each timer is implemented as a 16-bit register accessed as two separate bytes: a low byte (TL0 or TL1)
and a high byte (TH0 or TH1). The Timer Control register (TCON) is used to enable Timer 0 and Timer 1 as
well as indicate status. Timer 0 interrupts can be enabled by setting the ET0 bit in the IE register (Section
“8.3.5. Interrupt Register Descriptions” on page 61); Timer 1 interrupts can be enabled by setting the
ET1 bit in the IE register (Section 8.3.5). Both timers operate in one of four primary modes selected by set-
ting the Mode Select bits T1M1-T0M0 in the Timer Mode register (TMOD). Each timer can be configured
independently. Each operating mode is described below.
Rev. 0.5
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