EM6605 EM Microelectronic, EM6605 Datasheet - Page 10

• Manufacturer Part Number: EM6605
• Description: 4 bit Microcontroller
• Manufacturer: EM Microelectronic

6. INPUT and OUTPUT ports
The EM6605 has four independent 4-bit ports, as shown in Table 9.
Table 10.Input / Output Ports Overview
Port
PA(0:3)
PB(0:3)
PC(0:3)
PD(0:3)
Table 11.Option register - Option
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 2 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 Fig.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 Fig.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 EM6605 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 during two rising edges of ck[11] or ck[8]
clocks (1024Hz or 128Hz (*f1) at 32kHz). This corresponds to a worst case of tdebS or tdebL shown in table
6. PortA terminals PA0, PA1 and PA2 are also used as input conditions for conditional software branches as
shown on the next page:
© EM Microelectronic-Marin SA, 02/99, Rev. B/243
10
(*) Some options can be set also by Option Register .
Bit
3
2
1
0
Mode
Input
Individual
input or output
Port input or output
Port input or Output
Name
IRQedgeR
debPCN
debPAN
NoWD
Mask Options
Pull-Up/Down
(*) Debouncer
(*) + or - IRQ edge
RESET combination
Nch open drain output
Pull-Up/Down on input
Pull-Up/Down
(*) + or - IRQ edge
(*) Debouncer
Nch open drain output
Pull-Up/Down on Input
Nch open drain output
Reset
0
0
0
0
R/W
R/W
R/W
R/W
R/W
Function(s)
Input Interrupt
Software Test Variable
PA3 input for event counter
RESET input(s)
Input or Output
PB0 for buzzer output
Input or Output Port
Interrupt
Input or Output Port
PD0 -SWB serial clock output
PD1 -SWB serial data output
Rising edge interrupt for portA&C
PortC without/with debouncer
PortA without/with debouncer
WatchDog timer Off
Description
EM6605