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62 CMX158886 cpuModule BDM-610000049 Rev G
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). 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
three modes are strobe, match and event. Strobe mode generates an interrupt and latches Port 0 when the strobe
input transitions from low to high. 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 any 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 454h. These
registers are written to zero upon power up. From 450h to 454h, the name of these registers are Port 0 data,
Port 1 data, Multi-Function, DIO-Control, and Wake Control register.
Digital I/O Register Set
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.
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 aDIO connector. A write on this register when it is programmed
as output will write the value to the aDIO connector. A read on this register when it is set to output will read the
last value sent to the aDIO connector.
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.
Note RTD provides drivers that support the aDIO interface on popular operating systems. RTD
recommends using these drivers instead of accessing the registers directly.
Table 44 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
Table 45 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
Table 46 Multi-Function I/O Address 452h
D7 D6 D5 D4 D3 D2 D1 D0