C8051F120 Datasheet, PDF (314/356 Pages) Silicon Laboratories – Mixed Signal ISP Flash MCU Family

C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
The C/T0 bit (TMOD.2) selects the counter/timer's clock source. When C/T0 is set to logic 1, high-to-low
transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section
“18.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 242 for information on selecting and
configuring external I/O pins). Clearing C/T selects the clock defined by the T0M bit (CKCON.3). When
T0M is set, Timer 0 is clocked by the system clock. When T0M is cleared, Timer 0 is clocked by the source
selected by the Clock Scale bits in CKCON (see Figure 23.6).
Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal
/INT0 is logic-level 1. Setting GATE0 to ‘1’ allows the timer to be controlled by the external input signal /
INT0 (see Section “11.7.5. Interrupt Register Descriptions” on page 159), facilitating pulse width measure-
ments.
TR0
GATE0
0
X
1
0
1
1
1
1
X = Don't Care
/INT0
X
X
0
1
Counter/Timer
Disabled
Enabled
Disabled
Enabled
Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial
value before the timer is enabled.
TL1 and TH1 form the 13-bit register for Timer 1 in the same manner as described above for TL0 and TH0.
Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0. The
input signal /INT1 is used with Timer 1.
Pre-scaled Clock
SYSCLK
T0
Crossbar
GATE0
CKCON
TT SS
1 0 CC
MM A A
10
TMOD
GCT TGCT T
A / 11A / 00
T T MMT T MM
E110E010
1
0
0
0
1
1
TR0
TCLK
TL0
(5 bits)
TH0
(8 bits)
TF1
TR1
TF0
Interrupt
TR0
IE1
IT1
IE0
IT0
/INT0
Figure 23.1. T0 Mode 0 Block Diagram
314
Rev. 1.3