c8051f410 Silicon Laboratories, c8051f410 Datasheet - Page 240

• Manufacturer Part Number: c8051f410
• Description: 2.0 V, 32/16 Kb Flash, Smartclock, 12-bit Adc
• Manufacturer: Silicon Laboratories

C8051F410/1/2/3
24.2.2. 8-bit Timers with Auto-Reload
When T2SPLIT is set, Timer 2 operates as two 8-bit timers (TMR2H and TMR2L). Both 8-bit timers oper-
ate in auto-reload mode as shown in Figure 24.5. TMR2RLL holds the reload value for TMR2L; TMR2RLH
holds the reload value for TMR2H. The TR2 bit in TMR2CN handles the run control for TMR2H. TMR2L is
always running when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 2 Clock Select bits (T2MH and T2ML in CKCON) select either SYSCLK or
the clock defined by the Timer 2 External Clock Select bit (T2XCLK in TMR2CN), as follows:
The TF2H bit is set when TMR2H overflows from 0xFF to 0x00; the TF2L bit is set when TMR2L overflows
from 0xFF to 0x00. When Timer 2 interrupts are enabled (IE.5), an interrupt is generated each time
TMR2H overflows. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an interrupt is gener-
ated each time either TMR2L or TMR2H overflows. When TF2LEN is enabled, software must check the
TF2H and TF2L flags to determine the source of the Timer 2 interrupt. The TF2H and TF2L interrupt flags
are not cleared by hardware and must be manually cleared by software.
240
External Clock / 8
T2MH
SYSCLK / 12
0
0
1
T2XCLK TMR2H Clock Source
T2XCLK
X
0
1
0
1
Figure 24.5. Timer 2 8-Bit Mode Block Diagram
SYSCLK
External Clock / 8
SYSCLK / 12
SYSCLK
0
1
1
0
M
H
T
3
T
M
3
L
CKCON
T
2
M
H
M
T
2
L
M
T
1
M
T
0
TR2
S
C
A
1
S
C
A
0
Rev. 1.0
TCLK
TCLK
TMR2RLH
TMR2RLL
TMR2H
TMR2L
T2ML
0
0
1
Reload
Reload
T2XCLK
X
0
1
T2SPLIT
TF2LEN
T2XCLK
TF2H
TF2L
TR2
TMR2L Clock Source
External Clock / 8
SYSCLK / 12
SYSCLK
Interrupt