Rainbow Electronics ATAR862-3 - Manual (Page 35)

35
ATAR862-3
4556B–4BMCU–02/03
Port 2 Data Register (P2DAT) Primary register address: "2"hex
* Bit 3 -> MSB, Bit 0 -> LSB
Port 2 Control Register (P2CR) Auxiliary register address: "2"hex
Value: 1111b means all pins in input mode
Bi-directional Port 5 As all other bi-directional ports, this port includes a bitwise programmable Control Reg-
ister (P5CR), which allows the individual programming of each port bit as input or
output. It also opens up the possibility of reading the pin condition when in output mode.
This is a useful feature for self testing and for serial bus applications.
The port pins can also be used as external interrupt inputs (see Figure 23 and Figure
24). The interrupts (INT1 and INT6) can be masked or independently configured to trig-
ger on either edge. The interrupt configuration and port direction is controlled by the Port
5 Control Register (P5CR). An additional low resistance pull-up/-down transistor mask
option provides an internal bus pull-up for serial bus applications.
The Port 5 Data Register (P5DAT) is I/O mapped to the primary address register of
address "5"h and the Port 5 Control Register (P5CR) to the corresponding auxiliary reg-
ister. The P5CR is a byte-wide register and is configured by writing first the low nibble
and then the high nibble (see section "Addressing Peripherals").
Bit 3 * Bit 2 Bit 1 Bit 0
P2DAT3 P2DAT2 P2DAT1 P2DAT0 Reset value: 1111b
Bit 3 Bit 2 Bit 1 Bit 0
P2CR3 P2CR2 P2CR1 P2CR0 Reset value: 1111b
Code
3 2 1 0 Function
x x x 1 BP20 in input mode
x x x 0 BP20 in output mode
x x 1 x BP21 in input mode
x x 0 x BP21 in output mode
x 1 x x BP22 in input mode
x 0 x x BP22 in output mode
1 x x x BP23 in input mode
0 x x x BP23 in output mode