C8051F336/7/8/9
SFR Definition 24.13. TMR3CN: Timer 3 Control
Bit
7
6
5
4
3
2
1
0
Name
Type
Reset
TF3H
R/W
TF3L
R/W
TF3LEN
R/W
TF3CEN T3SPLIT
TR3
R/W
T3XCLK[1:0]
R/W
R/W
0
R/W
0
0
0
0
0
0
0
SFR Address = 0x91
Bit
Name
Function
7
TF3H
Timer 3 High Byte Overflow Flag.
Set by hardware when the Timer 3 high byte overflows from 0xFF to 0x00. In 16 bit
mode, this will occur when Timer 3 overflows from 0xFFFF to 0x0000. When the
Timer 3 interrupt is enabled, setting this bit causes the CPU to vector to the Timer 3
interrupt service routine. This bit is not automatically cleared by hardware.
6
TF3L
Timer 3 Low Byte Overflow Flag.
Set by hardware when the Timer 3 low byte overflows from 0xFF to 0x00. TF3L will
be set when the low byte overflows regardless of the Timer 3 mode. This bit is not
automatically cleared by hardware.
5
4
TF3LEN
TF3CEN
Timer 3 Low Byte Interrupt Enable.
When set to ‘1’, this bit enables Timer 3 Low Byte interrupts. If Timer 3 interrupts are
also enabled, an interrupt will be generated when the low byte of Timer 3 overflows.
Timer 3 Low-Frequency Oscillator Capture Enable.
When set to ‘1’, this bit enables Timer 3 Low-Frequency Oscillator Capture Mode. If
TF3CEN is set and Timer 3 interrupts are enabled, an interrupt will be generated on
a falling edge of the low-frequency oscillator output, and the current 16-bit timer
value in TMR3H:TMR3L will be copied to TMR3RLH:TMR3RLL.
3
2
T3SPLIT
TR3
Timer 3 Split Mode Enable.
When this bit is set, Timer 3 operates as two 8-bit timers with auto-reload.
0: Timer 3 operates in 16-bit auto-reload mode.
1: Timer 3 operates as two 8-bit auto-reload timers.
Timer 3 Run Control.
Timer 3 is enabled by setting this bit to ‘1’. In 8-bit mode, this bit enables/disables
TMR3H only; TMR3L is always enabled in split mode.
1:0 T3XCLK[1:0] Timer 3 External Clock Select.
This bit selects the “external” clock source for Timer 3. If Timer 3 is in 8-bit mode,
this bit selects the external oscillator clock source for both timer bytes. However, the
Timer 3 Clock Select bits (T3MH and T3ML in register CKCON) may still be used to
select between the external clock and the system clock for either timer.
00: System clock divided by 12.
01: External clock divided by 8 (synchronized with SYSCLK when not in suspend).
10: Reserved.
11: Internal LFO / 8 (synchronized with SYSCLK when not in suspend).
206
Rev. 0.2
SILICON [ SILICON ]
