Impulse PIO-48.PC104 (3701) - Manual (Page 14)

© Sealevel Systems, Inc. - 12 - PIO-48.PC104 User Manual
Presetting an Output Port
Each port has an output register associated with it. This register may be written and
retains its value whether the port is configured as an input or an output. To preset the
value of an output port the program should write to the port when it is configured as
an input then configure it as an output.
Writing the Outputs
The outputs are active high. Writing a one (1) corresponds to 5V while writing a
zero (0) corresponds to 0V, at the output.
Port C
Port C is written and read to as two four bit ports. If both lower and upper nibbles
are configure the same then no special considerations need to be made. But if they
are configured differently, one nibble as input, and one as output then the user will
have to keep this in mind. When reading, the input will be returned on the
corresponding upper or lower nibble while the current outputs will be returned on
their corresponding upper or lower nibble. When writing, the corresponding nibble
will be written to the output nibble, while the input nibble will have its output
register written to. The output register can be written to without affecting the inputs.
Register Description
Address Mode D7 D6 D5 D4 D3 D2 D1 D0
Base+0 Port A1 RD/WR PA1D7 PA1D6 PA1D5 PA1D4 PA1D3 PA1D2 PA1D1 PA1D0
Base+1 Port B1 RD/WR PB1D7 PB1D6 PB1D5 PB1D4 PB1D3 PB1D2 PB1D1 PB1D0
Base+2 Port C1 RD/WR PC1D7 PC1D6 PC1D5 PC1D4 PC1D3 PC1D2 PC1D1 PC1D0
Base+3 Control Word Port 1 WR 0 0 0 CW1D4 CW1D3 0 CW1D1 CW1D0
Base+4 Interrupt config Port 1 RD/WR 0 0 0 0 0 IRQEN1 IRQC11 IRQC10
Base+5 Interrupt status Port 1 and 2 RD 0 0 0 IRQST2 0 0 0 IRQST1
Base+8 Port A2 RD/WR PA2D7 PA2D6 PA2D5 PA2D4 PA2D3 PA2D2 PA2D1 PA2D0
Base+9 Port B2 RD/WR PB2D7 PB2D6 PB2D5 PB2D4 PB2D3 PB2D2 PB2D1 PB2D0
Base+A (10) Port C2 RD/WR PC2D7 PC2D6 PC2D5 PC2D4 PC2D3 PC2D2 PC2D1 PC2D0
Base+B (11) Control Word Port 2 WR 0 0 0 CW2D4 CW2D3 0 CW2D1 CW2D0
Base+C (12) Interrupt config Port 2 RD/WR 0 0 0 0 0 IRQEN2 IRQC21 IRQC20