PCM-MIO-A-1/Functionality
v1.0
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Page 6
3.1
Base I/O Address
The PCM-MIO-A-1 is I/O mapped and requires 32 sequential port
addresses. The base address is jumper selectable at
J7
. Care should be
taken to choose an I/O area that does not conflict with other resources in
the system. The specific device locations and register offsets are discussed
in more detail in “Software Summary” on page 17.
3.2
Interrupts
The PCM-MIO-A-1 provides flexible interrupt configuration options. Each
D/A converter and 24 digital I/O lines are capable of generating an
interrupt. They can be setup to use individual interrupts, a single shared
interrupt, or any combination of the two. The interrupts are completely
software configurable and require no jumpers or other configuration. The
individual registers and configuration for each device are discussed in
“Software Summary” on page 17.
The PCM-MIO-A-1 can be configured to use IRQs 3, 4, 5, 6, 7, 9, 10, 11, 12,
14, or 15 depending on availability in the system. IRQs 0, 1, 2, 8, and 13 are
not supported.
3.3
Analog-to-Digital
The PCM-MIO-A-1 analog-to-digital conversion inputs are implemented by
using two, 16-bit Linear Technology LTC-1859CG devices. The board
supports up to 16 single-ended input channels, 8 differential input
channels or various combinations of both. The channel configuration
word selects whether an input operates in single-ended or differential
mode and also selects the desired input range (0 V to 5 V, 0 V to 10 V, ±5 V
and ±10 V).
The LTC-1859CG uses a successive approximation algorithm and an
internal sample-and-hold circuit to convert an analog input signal to 16-bit
digital data. The output is two’s complement binary for bipolar mode and
offset binary for unipolar mode.
3.4
Digital-to-Analog
The PCM-MIO-A-1 provides digital-to-analog conversion using two 12-bit
Linear Technology LTC-2704 devices. These SoftSpan™ quad digital-to-
analog converters (DACs) are software programmable for either unipolar
or bipolar mode with specific voltage ranges on a per channel basis. Each
of the 8 channels can be programmed to any one of the output ranges
(0 V to 5 V, 0 V to 10 V, ±2.5 V, ±5 V, ±10 V and -2.5 V to 7.5 V).
