Rainbow Electronics ATAR862-3 - Manual (Page 38)

38
ATAR862-3
4556B–4BMCU–02/03
Port 4 Data Register (P4DAT) Primary register address: "4"hex
Port 4 Control Register (P4CR)
Byte Write Auxiliary register address: "4"hex
P4xM2, P4xM1 – Port 4x Interrupt mode/direction code
Bi-directional Port 6 The bi-directional Port 6 is a bitwise configurable I/O port and provides the external pins
for the Timer 3. As a normal port, it performs in exactly the same way as bi-directional
Port 6 (see Figure 25). Two additional multiplexes allow data and port direction control
to be passed over to other internal module (Timer 3). The I/O-pin for T3I line has an
additional mode to generate a Timer 3-interrupt.
All two Port 6 pins can be individually switched by the P6CR register . Figure 25 shows
the internal interfaces to bi-directional Port 6.
Bit 3 Bit 2 Bit 1 Bit 0
P4DAT3 P4DAT2 P4DAT1 P4DAT0 Reset value: 1111b
Bit 3 Bit 2 Bit 1 Bit 0
First write cycle P41M2 P41M1 P40M2 P40M1 Reset value: 1111b
Bit 7 Bit 6 Bit 5 Bit 4
Second write cycle P43M2 P43M1 P42M2 P42M1 Reset value: 1111b
Auxiliary Address: "4"hex
First Write Cycle Second Write Cycle
Code
3 2 1 0 Function
Code
3 2 1 0 Function
x x 1 1 BP40 in input mode x x 1 1 BP42 in input mode
x x 1 0 BP40 in output mode x x 1 0 BP42 in output mode
x x 0 1 BP40 enable alternate function
(SC for SSI) x x 0 x BP42 enable alternate function
(T2O for Timer 2)
x x 0 0 BP40 enable alternate function
(falling edge interrupt input for
INT3) 1 1 x x BP43 in input mode
1 1 x x BP41 in input mode 1 0 x x BP43 in output mode
1 0 x x BP41 in output mode 0 1 x x BP43 enable alternate function
(SD for SSI)
0 1 x x BP41 enable alternate function
(VMI for voltage monitor input) 0 0 x x BP43 enable alternate function
(falling edge interrupt input for
INT3)
0 0 x x BP41 enable alternate function
(T2I external clock input for
Timer 2) – –