Samsung KS57C2308 manual TC0 Clock Frequency Output, TREF0,EA EA,#4CH TMOD0,EA, Bits TOE0

KS57C2308/P2308/C2316/P2316 TIMERS and TIMER/COUNTERS

TC0 CLOCK FREQUENCY OUTPUT

Using timer/counter 0, a modifiable clock frequency can be output to the TC0 clock output pin, TCLO0. To select the clock frequency, load the appropriate values to the TC0 mode register, TMOD0. The clock interval is selected by loading the desired reference value into the reference register TREF0. To enable the output to the TCLO0 pin, the following conditions must be met:

—TC0 output enable flag TOE0 must be set to "1"

—I/O mode flag for P2.0 must be set to output mode ("1")

—Output latch value for P2.0 must be set to "0"

In summary, the operational sequence required to output a TC0-generated clock signal to the TCLO0 pin is as follows:

1.Load a reference value to TREF0.

2.Set the internal clock frequency in TMOD0.

3.Initiate TC0 clock output to TCLO0 (TMOD0.2 = "1").

4.Set P2.0 mode flag to "1".

5.Clear P2.0 output latch to "0".

6.Set TOE0 flag to "1".

Each time TCNT0 overflows and an interrupt request is generated, the state of the output latch TOL0 is inverted and the TC0-generated clock signal is output to the TCLO0 pin.

+PROGRAMMING TIP — TC0 Signal Output to the TCLO0 Pin

Output a 30 ms pulse width signal to the TCLO0 pin:

BITS	EMB
SMB	15
LD	EA,#79H
LD	TREF0,EA
LD	EA,#4CH
LD	TMOD0,EA
LD	EA,#04H
LD	PMG2,EA	; P2.0 ← output mode
BITR	P2.0	; Clear P2.0 output latch
BITS	TOE0

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