C8051F120/1/2/3/4/5/6/7
Rev. 1.2
287
24.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configures Timer 0 and 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 initial-
ized to the desired value before enabling the timer for the first count to be correct. 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.
Figure 24.2. T0 Mode 2 Block Diagram
TCLK
TMOD
T
1
M
1
T
1
M
0
C
/
T
1
G
A
T
E
1
G
A
T
E
0
C
/
T
0
T
0
M
1
T
0
M
0
TCO
N
TF0
TR0
TR1
TF1
IE1
IT1
IE0
IT0
Interrupt
TL0
(8 bits)
Reload
TH0
(8 bits)
0
1
0
1
SYSCLK
Pre-scaled Clock
CKCON
S
C
A
0
S
C
A
1
T
1
M
T
0
M
TR0
GATE0
/INT0
T0
Crossbar
Summary of Contents for C8051F120
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Page 8: ...C8051F120 1 2 3 4 5 6 7 8 Rev 1 2 26 2 Flash Programming Commands 318 26 3 Debug Support 321 ...
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