EMAC MicroPac 535, Справочник по аппаратуре

Страница: 17 / 27

13
SIGNAL OUTPUTS
For applications that need a signal output, there are 3 sources available:
CLOCKOUT this can be programmed to provide a system clock output of 1/12 the oscillator frequency.
OP2 this can output channel A's transmitter clock, transmitter clock times 16, or receiver clock.
OP3 this can output channel B's transmitter clock, receiver clock, or the C/T output
WATCHDOG TIMER
The watchdog timer is built into the SAB 80535 processor and is used to reset the MicroPac 535 in the event that a hardware or software
crash occurs. When the watchdog timer is enabled the software must clear the timer at least once every 65532 machine cycles (a
machine cycle is 1/12 of the oscillator frequency), otherwise a reset will occur. This reset is the same as an external reset, except that bit
WDTS (bit 6 of IP0) is set. Using this, the software can determine the source of the reset.
To enable the watchdog timer (it is disabled by default), set the SWDT bit which is bit 6 of IEN1. Once it has been enabled, the only way it
can be disabled is through an external reset. Once it is enabled, to clear the timer you must set the WDT bit (IEN0.6) and then the SWDT
bit. The requirement of setting two bits independently lessens the possibility of a crashing program from clearing the watchdog timer. See
also section 3.7 of the SAB 80515/80535 Single-Chip Microcontroller User's Manual included in the appendices.
INTERRUPTS
The 80535 has 5 internal interrupt sources and 7 external sources, and the SC26C92 has a
single interrupt output with eight maskable interrupt sources. As these devices are configured
on the MicroPac 535, this works out to 9 external interrupt sources (10 available when timer 2
reload mode is disabled) and 9 on-board. The external interrupts IP0 and IP1 are available on
the expansion connector (the connector is discussed later) and the rest are all available on
HDR3. For more information on 80535 interrupts, see section 3.6 of the SAB 80515/80535
Single-Chip Microcontroller User's Manual included in the appendices. The interrupt sources are
as follows:
EXTERNAL
INT2* (programmable for rising or falling edge trigger)
INT3* (programmable for rising or falling edge trigger)
INT4 (rising edge triggered)
INT5 (rising edge triggered)
INT6 (rising edge triggered)
T2EX/P1.5 (when timer 2 reload mode is disabled, it is falling edge triggered)
Through INT0/P3.2 the following SC26C92 interrupts are detected:
IP0 (rising AND falling edge triggered)
IP1 (rising AND falling edge triggered)
IP2 (rising AND falling edge triggered)
IP3 (rising AND falling edge triggered)
INTERNAL
A/D Convertor
Timer 0
Timer 1
Timer 2
COM0
(80535 serial port)
INT1/P3.3 (keypad)
EXTERNAL
DIGITAL I/O
HDR3
50 49
GND o o VCC
GND o o PX0 P4.0
GND o o PX1 P4.1
GND o o PX2 P4.2
GND o o PX3 P4.3
GND o o PX4 P4.4
GND o o PX5 P4.5
GND o o PX6 P4.6
GND o o PX7 P4.7
GND o o PX8 P1.O/INT3*/CC0
GND o o PX9 P1.1/INT4/CC1
GND o o PX10 P1.2/INT5/CC2
GND o o PX11 P1.3/INT6/CC3
GND o o PX12 P1.4/INT2*
GND o o PX13 P1.5/T2EX
GND o o PX14 P1.6/CLKOUT
GND o o PX15 P1.7/T2
GND o o PX16 P3.4/TO
GND o o PX17 P3.5/T1
GND o o PX18 OP2
GND o o PX19 IP2
GND o o PX20 OP3
GND o o PX21 IP3
GND o o PX22 OP4
GND o o PX23 IP6
2 1