IBM CMX58886CX user manual MultiPort Advanced Digital I/O Ports aDIO, Digital I/O Register Set

multiPort: Advanced Digital I/O Ports (aDIO™)

Ensure that the BIOS setup has the multiPort set to aDIO mode. This board supports 16 bits of TTL/CMOS compatible digital I/O (TTL signaling). Use the BIOS setup to set the multiPort into its aDIO mode. These I/O lines are grouped into two ports, Port 0 and Port 1. Port 0 is bit programmable; Port 1 is byte programmable. Port 0 supports RTD’s Advanced Digital Interrupt modes. The two modes are match and event. Match mode generates an interrupt when an 8-bit pattern is received in parallel that matches the match mask register. Event mode generates an interrupt when a change occurs on any bit. In either mode, masking can be used to monitor selected lines.

When the CPU boots, all digital I/O lines are programmed as inputs, meaning that the digital I/O line’s initial state is undetermined. If the digital I/O lines must power up to a known state, an external 10 kΩ resistor must be added to pull the line high or low.

The 8-bit control read/write registers for the digital I/O lines are located from I/O address 450h to 453h. These registers are written to zero upon power up. From 450h to 453h, the name of these registers are Port 0 data, Port 1 data, Multi-Function, and DIO-Controlregister.

Note RTD provides drivers that support the aDIO interface on popular operating systems. RTD recommends using these drivers instead of accessing the registers directly.

Digital I/O Register Set

Table 39 Port 0 Data I/O Address 450h

D7	D6	D5	D4	D3	D2	D1	D0
P0.7	P0.6	P0.5	P0.4	P0.3	P0.2	P0.1	P0.0

Port 0 Data register is a read/write bit direction programmable register. A particular bit can be set to input or output. A read of an input bit returns the value of port 0. A read of an output bit returns the last value written to Port 0. A write to an output bit sends that value to port 0.

Table 40 Port 1 Data I/O Address 451h

D7	D6	D5	D4	D3	D2	D1	D0
P1.7	P1.6	P1.5	P1.4	P1.3	P1.2	P1.1	P1.0

Port 1 Data register is a read/write byte direction programmable register. A read on this register when it is programmed to input will read the value at the multiPort connector. A write on this register when it is programmed as output will write the value to the multiPort connector. A read on this register when it is set to output will read the last value sent to the multiPort connector.

Table 41 Multi-Function I/O Address 452h

D7 D6 D5 D4 D3 D2 D1 D0

The multi-function register is a read/write register whose contents are set by the DIO-Control register. See the DIO-Control register description for a description of this register.

56 CMX58886CX cpuModule BDM-610000050 Rev A