EM78P468LAQ EMC [ELAN Microelectronics Corp], EM78P468LAQ Datasheet - Page 31

• Manufacturer Part Number: EM78P468LAQ
• Description: 8-BIT Microcontroller
• Manufacturer: EMC [ELAN Microelectronics Corp]

Product Specification (V1.0) 03.15.2006
(This specification is subject to change without further notice)
4.3 TCC and WDT Pre-scaler
4.2.19 IOCC1/P6OD (PORT 6 Open Drain Control Register)
4.2.20 IOCD1/P8PH (PORT 8 Pull High Control Register)
4.2.21
Bit 7 ~ Bit 0: The enable bits of PORT 6 open drain function.
Bit 7 ~ Bit 0: The enable bits of PORT 8 pull-high function.
Bit 7 ~ Bit 0: The enable bits of PORT 6 pull low function.
Two 8-bit counters are available as pre-scalers for the TCC (Time Clock Counter) and
WDT (Watch Dog Timer). The TCCP2~TCCP0 bits of the IOC71 register are used to
determine the ratio of the TCC pre-scaler. Likewise, the WDTP2~WDTP0 bits of the
IOC81 register are used to determine the WDT pre-scaler. The TCC pre-scaler
(TCCP2~TCCP0) is cleared by the instructions each time they are written into TCC,
while the WDT pre-scaler is cleared by the “WDTC” and “SLEP” instructions. Fig.7
depicts the circuit diagram of TCC and WDT.
R1 (TCC) is an 8-bit timer/counter. The clock source of TCC can be selected by internal
instruction clock or external signal input (edge selectable from the TCC control register).
If TCC signal source is from internal instruction clock, TCC will increase by 1 at every
instruction cycle (without pre-scaler). If TCC signal source is from external clock input,
TCC will increase by 1 at every falling edge or rising edge of the TCC pin.
The watchdog timer is a free running on sub-oscillator. The WDT will keep on running
even after the oscillator driver has been turned off. During Normal mode, Green mode, or
OP67
PH87
PL67
Bit 7
Bit 7
Bit 7
OD6x = “0”: disable pin of P6.x open drain function
OD6x = “1”: enable pin of P6.x open drain function
PH8x = ”0”: disable pin of P8.x internal pull-high resistor function
PH8x = “1”: enable pin of P8.x pull-high resistor function
PL6x = “0”: disable pin of P6.x internal pull-low resistor function
PL6x = “1”: enable pin of P6.x internal pull-low resistor function
(Address: 0Ch, Bit 0 of R5 = “1”)
(Address: 0Dh, Bit 0 of R5 = “1”)
(Address: 0Eh, Bit 0 of R5 = “1”)
IOCE1/P6PL (PORT 6 Pull-Low Control Register)
OP66
PH86
PL66
Bit 6
Bit 6
Bit 6
OP65
PH85
PL65
Bit 5
Bit 5
Bit 5
OP64
PH84
PL64
Bit 4
Bit 4
Bit 4
OP63
PH83
PL63
Bit 3
Bit 3
Bit 3
OP62
PH82
PL62
Bit 2
Bit 2
Bit 2
8-BIT Microcontroller
OP61
PH81
PL61
Bit 1
Bit 1
Bit 1
EM78P468L
OP60
PH80
PL60
Bit 0
Bit 0
Bit 0
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