Timer 3 Register - CMOSTEK CMT2380F17 Manual

How to Program Split Timer 3 in Clock-out Mode
•
Select TL3 clock source.
•
Determine the 8-bit reload value from the formula and enter it in the RCAP3L register.
•
Enter the same reload value as the initial value in the TL3 register.
•
Set T3OE bit in T3MOD register.
•
Set TR3L bit in T3CON register to start the Timer 3.
In the Clock-Out mode, TL3 rollovers will not generate an interrupt, TF3L. This is similar to when TL3 is
used as a baud-rate generator. It is possible to use TL3 as a baud rate generator and a clock generator
simultaneously. Note, however, that the baud-rate and the clock-out frequency depend on the same overflow
rate of TL3 in split Timer 3. The TF3L interrupt is enabled by TL3IE in T3CON register.

16.3.11 Timer 3 Register


T3CON：Timer 3 Control Register
SFR Page = 1 Only
SFR Address = 0xC8
Bit
7
Name TF3
R/W R/W
Reset V alue 0
Bit 7: TF3, Timer 3 overflow flag.
0: TF3 must be cleared by software.
1: TF3 is set by a Timer 3 overflow happens.
Bit 6: EXF3, Timer 3 external flag.
0: EXF3 must be cleared by software.
1: Timer 3 external flag set when either a capture or reload is caused by a negative transition on T3EX
pin and EXEN3=1 or a positive transition on T3EX and T3EXH=1. When Timer 3 interrupt is enabled,
EXF3=1 will cause the CPU to vector to the Timer 3 interrupt routine. When the MCU is in power-down
mode and Timer 3 interrupt is enabled, the EXF3 is forced to level-sensitive triggered with wake-up MCU
capability.
Bit 5: TF3L, TL3 overflow flag in Timer 3 split mode.
0: TF3L must be cleared by software.
1: TF3L is set by TL3 overflow happened in Timer 3 split mode.
Bit 4: TL3IE, TF3L interrupt enable.
0: Disable TF3L interrupt.
1: Enable TF3L interrupt to share the Timer 3 interrupt vector.
Bit 3: EXEN3, Timer 3 external enable flag on a negative transition of the Timer 3 external input.
0: Cause Timer 3 to ignore negative transition events at Timer 3 external input.
1: Allows a capture or reload to occur as a result of a 1-to-0 transition on Timer 3 external input. If Timer 3
Figure 16-39. Split Timer 3 in Clock-Out Mode
6 5
EXF3 TF3L
R/W R/W
0 0
Rev0.1 | 166/347
4 3
TL3IE EXEN3
R/W R/W
0 0
CMT2380F17
2 1
TR3 C/T3
R/W R/W
0 0
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0
CP/RL3
R/W
0