C8051F850-C-GM Datasheet, PDF (278/328 Pages) Silicon Laboratories – Low-Cost 8-bit MCU Family with up to 8 kB of Flash

25.1.3. 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 all
ones to 0x00, the timer overflow flag TF0 in the TCON register 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 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 enables the timer when either GATE0 in the TMOD register is logic 0 or when the input signal INT0
is active as defined by bit IN0PL in register IT01CF.
T0M
CT0
Pre-scaled Clock
0
0
SYSCLK
1
1
T0
TR0
GATE0
TCLK
TL0
(8 bits)
TF0
(Interrupt Flag)
INT0
IN0PL _XOR
TH0
(8 bits)
Reload
Figure 25.2. T0 Mode 2 Block Diagram
250
Rev. 1.0