Mode 1: 16-Bit Counter/Timer; Mode 2: 8-Bit Counter/Timer With Auto-Reload; Figure 23.2. T0 Mode 2 Block Diagram - Silicon Laboratories C8051F12 Series Manual

C8051F120/1/2/3/4/5/6/7 C8051F130/1/2/3

23.1.2. Mode 1: 16-bit Counter/Timer

Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The
counter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.

23.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload

Mode 2 configures Timer 0 or Timer 1 to operate as 8-bit counter/timers with automatic reload of the start
value. TL0 holds the count and TH0 holds the reload value. When the counter in TL0 overflows from 0xFF
to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0. If Timer
0 interrupts are enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is not
changed. TL0 must be initialized to the desired value before enabling the timer for the first count to be cor-
rect. When in Mode 2, Timer 1 operates identically to Timer 0.
Both counter/timers are enabled and configured in Mode 2 in the same manner as Mode 0. Setting the
TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or when the input signal /INT0
is low
.
Pre-scaled Clock
SYSCLK
T0
Crossbar
/INT0
CKCON
T T S S G
A
1 0 C C
T
M M A A
E
1 0
1
0
0
1
1
TR0
GATE0

Figure 23.2. T0 Mode 2 Block Diagram

TMOD
C T T G C T T
/ 1 1 A / 0 0
T M M T T M M
1 1 0 E 0 1 0
0
TCLK TL0
(8 bits)
TH0
Reload
(8 bits)
Rev. 1.4
TF1
TR1
TF0 Interrupt
TR0
IE1
IT1
IE0
IT0
311