Introducing The Pci-Dio24H; Functional Block Diagram - Measurement Computing PCI-DIO24H User Manual

Introducing the PCI-DIO24H

This manual explains how to install and use the PCI-DIO24H board. The PCI-DIO24H is a high output drive,
logic-level digital I/O board designed for the PCI-bus.
The PCI-DIO24H provides 24-bits of digital I/O in three eight-bit ports (Port A, Port B, and Port C) based on an
82C55 mode 0 emulation. Port C can be further divided into two four-bit ports (Port C-HI and Port C-LO). You
can configure each port independently for either input or output.
All digital inputs are LSTTL. The output signals are buffered high output drive TTL. The digital output drivers
are 74S244 chips that can sink 64 mA and source 15 mA. The input buffers are 74LS373 chips and have
standard high input impedance of the 74LS series devices.
All 24 I/O lines are accessible through the board's 37-pin connector.
82C55 Mode 0 programming supported
The PCI-DIO24H supports 82C55 Mode 0 programming only.

Functional block diagram

PCI-DIO24H functions are illustrated in the block diagram shown here.
82C55 Mode 0 Emulation
PORT A (7:0)
PORT B (7:0)
PORT CH (3:0)
PORT CL (3:0)
+5V
+12V
-12V
High Drive
PORT A
Control
Bus
PORT B
PORT CH
PORT CL
Local Bus
Boot
EEPROM
Figure 1. Functional block diagram
Controller FPGA and logic
Control
Registers
Interrupt
Decode/Status
Control
Bus
Timing
BADR1
PCI
BADR2
Controller
Interrupt
PCI BUS (5V, 32-bit, 33 MHZ)
5
Chapter 1
IRQ INPUT
IRQ ENABLE