19.4.21 TMR4CN0: Timer 4 Control 0
Bit
7
6
5
4
3
2
1
0
Name
TF4H
TF4L
TF4LEN
TF4CEN
T4SPLIT
TR4
T4XCLK
Access
RW
RW
RW
RW
RW
RW
RW
Reset
0
0
0
0
0
0
0x0
SFR Page = 0x10; SFR Address: 0x98 (bit-addressable)
Bit
Name
Reset
Access Description
7
TF4H
0
RW
Timer 4 High Byte Overflow Flag.
Set by hardware when the Timer 4 high byte overflows from 0xFF to 0x00. In 16-bit mode, this will occur when Timer 4
overflows from 0xFFFF to 0x0000. When the Timer 4 interrupt is enabled, setting this bit causes the CPU to vector to the
Timer 4 interrupt service routine. This bit must be cleared by firmware.
6
TF4L
0
RW
Timer 4 Low Byte Overflow Flag.
Set by hardware when the Timer 4 low byte overflows from 0xFF to 0x00. TF4L will be set when the low byte overflows
regardless of the Timer 4 mode. This bit must be cleared by firmware.
5
TF4LEN
0
RW
Timer 4 Low Byte Interrupt Enable.
When set to 1, this bit enables Timer 4 Low Byte interrupts. If Timer 4 interrupts are also enabled, an interrupt will be gen-
erated when the low byte of Timer 4 overflows.
4
TF4CEN
0
RW
Timer 4 Capture Enable.
When set to 1, this bit enables Timer 4 Capture Mode. If TF4CEN is set and Timer 4 interrupts are enabled, an interrupt will
be generated according to the capture source selected by the T4CSEL bits, and the current 16-bit timer value in
TMR4H:TMR4L will be copied to TMR4RLH:TMR4RLL.
3
T4SPLIT
0
RW
Timer 4 Split Mode Enable.
When this bit is set, Timer 4 operates as two 8-bit timers with auto-reload.
Value
Name
Description
0
16_BIT_RELOAD
Timer 4 operates in 16-bit auto-reload mode.
1
8_BIT_RELOAD
Timer 4 operates as two 8-bit auto-reload timers.
2
TR4
0
RW
Timer 4 Run Control.
Timer 4 is enabled by setting this bit to 1. In 8-bit mode, this bit enables/disables TMR4H only; TMR4L is always enabled in
split mode.
1:0
T4XCLK
0x0
RW
Timer 4 External Clock Select.
T4XCLK selects the external clock source for Timer 4. If Timer 4 is in 8-bit mode, T4XCLK selects the external oscillator
clock source for both timer bytes. However, the Timer 4 Clock Select bits (T4MH and T4ML) may still be used to select
between the external clock and the system clock for either timer.
Value
Name
Description
0x0
SYSCLK_DIV_12
Timer 4 clock is the system clock divided by 12.
0x1
EXTOSC_DIV_8
Timer 4 clock is the external oscillator divided by 8 (synchronized with
SYSCLK).
0x2
TIMER3
Timer 4 is clocked by Timer 3 overflows.
0x3
LFOSC_DIV_8
Timer 4 clock is the low-frequency oscillator divided by 8 (synchronized
with SYSCLK).
EFM8UB3 Reference Manual
Timers (Timer0, Timer1, Timer2, Timer3, Timer4, and Timer5)
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