A8255 Datasheet PDF | Altera Corporation

Altera Corporation A8255

The a8255 MegaCore function implements a programmable peripheral interface adapter (see Figure 1). The a8255 has 24 I/O signals that can be programmed in two groups of 12. This MegaCore function operates in the following three modes: s Mode 0: Basic Input/Output—Port A, port B, and port C (upper and lower) can be independently configured as inputs or outputs to read or hold static data.

Part No.	A8255
Datasheet	A8255 Download
Manufacturer	Altera Corporation
Description	PROGRAMMABLE PERIPHERAL INTERFACE ADAPTER
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GENERAL DESCRIPTION

s a8255 MegaCore function implementing a programmable peripheral interface adapter s Optimized for FLEX® and MAX® architectures s 24 programmable inputs/outputs s Static read/write or handshaking modes s Direct bit set/reset capability s Synchronous design s Uses approximately 194 FLEX logic elements (LEs) s Functionally based on the Intel 8255A and Harris 82C55A devices, except as noted in the “Variations & Clarifications” section on page 56 Outputs are registered; inputs are not registered. s Mode 1: Strobed Input/Output—Port A and port B can be independently configured as strobed input or output buses. Signals from port C are dedicated as control signals for data handshaking. s Mode 2: Bidirectional Bus—Port A can be configured as a bidirectional bus with the majority of port C providing the control signals. In this configuration, port B can still implement mode 0 or mode 1. Figure 1. a8255 Symbol A8255 CLK nCS nRD nWR RESET A[1..0] DIN[7..0] PAin[7..0]...