EM6603
6
INPUT and OUTPUT ports
The EM6603 has four independent 4-bit ports, as shown in Table 9
Table 9.Input / Output Ports Overview
Port
Mode
Mask Options
Function(s)
PA(0:3) Input
Pull-Up/Down
Input Interrupt
(*)Debouncer
Software Test Variable
PA3 input for event counter
RESET input(s)
(*) + or – IRQ edge
RESET combination
PB(0:3) Individual
Nch open drain output Input or Output
input or output
Pull-Up/Down on input PB0 for buzzer output
PC(0:3) Port input or output
Pull-Up/Down
Input or Output Port
Interrupt
(*)+ or – IRQ edge
(*)Debouncer
Nch open drain output
PD(0:3) Port input or Output Pull-Up/Down on Input Input or Output Port
Nch open drain output PD0 -SWB serial clock output
PD1 -SWB serial data output
(*) Some options can be set also by Option register .
Table 10.Option register - Option
Bit
Name
Reset
R/W
R/W
R/W
R/W
R/W
Description
3
IRQedgeR
debPCN
debPAN
NoWD
0
0
0
0
Rising edge interrupt for portA&C
PortC without/with debouncer
PortA without/with debouncer
WatchDog timer Off
2
1
0
IRQedgeR - Valid for both PortA and PortC input interrupt edge. At RESET it is cleared to 0 selecting the falling
edge at the input as the interrupt source. When set to 1 the rising edge is active. (option 3 on Fig 6 and Fig 8)
debPAN - by default after reset it is 0 enabling the debouncers on whole portA. Writing it to 1 removes the
debouncers from the PortA. (option 2 on Figure 6)
debPCN - by default after reset it is 0 enabling the debouncers on whole portC. Writing it to 1 removes the
debouncers from the PortC. (option 2 on Figure 8)
NoWD - by default after reset it is 0 = Watchdog timer is On. Writing it to 1 removes the WatchDog timer.
6.1 PortA
The EM6603 has one four bit general purpose input port. Each of the input port terminals PA3..PA0 has an
internal pull-Up/Down resistor which can be selected with mask options. Port information is read directly from
the pin into a register.
On inputs PA0, PA1, PA2 and PA3 debouncers for noise rejection are added by default. For interrupt
generation, one can choose between either direct input or debounced input. With the debPAN bit at 0 in the
Option register all the PortA inputs are debounced and with the debPAN bit at 1 none of the PortA inputs are
debounced. With the debouncer selected the input must be stable for two rising edges of 1024Hz or 128Hz
clocks (at 32kHz). This corresponds to a worst case of 1.95ms or 15.62msec. PortA terminals PA0, PA1 and
PA2 are also used as input conditions for conditional software branches as shown on the next page:
03/02 REV. G/439
9
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