NXP Semiconductors MC68302EH20CR2

Overview

MC68302EH20CR2 from Freescale Semiconductor is a single-chip integrated multi-protocol processor featuring an MC68000/MC68008 microprocessor core, a dedicated RISC-based communications processor (CP), and a system integration block (SIB). It operates at 20 MHz, integrates 1152 bytes of on-chip dual-port RAM, supports HDLC/SDLC, UART, Bisync, DDCMP, and Totally Transparent protocols via three full-duplex Serial Communication Controllers (SCCs), and targets ISDN terminal adapters and data concentrators.

For engineers reviewing the MC68302EH20CR2 datasheet, MC68302EH20CR2 pinout, MC68302EH20CR2 application, or MC68302EH20CR2 equivalent, key selection criteria include its 20 MHz clock speed, triple SCC + dual SMC architecture, HCMOS 132-pin TQFP package, support for concurrent protocol handling, and on-chip IDMA and watchdog timer functionality.

Technical Context

The MC68302EH20CR2 implements a tightly coupled dual-processor architecture: the MC68000/MC68008 core handles general-purpose execution while a separate RISC main controller in the CP manages serial protocol processing independently. This enables true hardware-level concurrency across HDLC, UART, and Bisync channels without CPU intervention.

Its system integration block provides bus arbitration with low interrupt latency, four programmable chip-select lines with wait-state logic, DRAM refresh control, and three timers including a software watchdog. The CP includes six serial DMA channels, SCP for synchronous communication, and two SMCs dedicated to IDL and GCI channel management.

Key Specifications

Pinout & Package

MC68302EH20CR2 is housed in a 132-pin Thin Quad Flat Pack (TQFP) package with 0.4 mm lead pitch and exposed thermal pad. Pin assignments follow Motorola/Freescale standard MC68302 derivative layout, supporting multiplexed address/data bus, dedicated serial interface pins (SCC/SMC/SCP), parallel I/O ports with interrupt capability, and system control signals including reset, clock, and bus arbitration lines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-protocol communications processor applications.

Compared with MC68EN302 and MC68LC302, the MC68302EH20CR2 uniquely balances 20 MHz performance, triple SCC flexibility, and proven ISDN protocol stack support in a mature 132-pin footprint - making it optimal for cost-sensitive, volume-deployed communications line cards where Ethernet or ultra-low power are not primary requirements.

Availability

MC68302EH20CR2 is available at Aetrix Electronics and suitable for ISDN terminal adapters, data concentrators, and legacy modem controller designs requiring stable component supply, long-term obsolescence management, and traceable sourcing.

Supply support for MC68302EH20CR2 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Freescale Semiconductor (now part of NXP) was a leading designer of embedded processors and analog/mixed-signal ICs, with deep expertise in automotive, industrial, and communications silicon.

The MC68302EH20CR2 belongs to Freescale's integrated communications processor family, engineered specifically for cost-effective, high-reliability implementations of ISDN, leased-line, and multi-protocol serial gateway systems.

FAQ

What is the maximum operating frequency of the MC68302EH20CR2?

The MC68302EH20CR2 is rated for a maximum operating frequency of 20 MHz, as indicated by the "H20" suffix in its part number. This frequency governs instruction cycle timing, serial baud rate generation accuracy, and real-time response limits for protocol handling. Operation above 20 MHz is not supported and may result in undefined behavior or data corruption in the MC68302EH20CR2.

Does the MC68302EH20CR2 include on-chip memory, and if so, what type and size?

Yes, the MC68302EH20CR2 integrates 1152 bytes of on-chip dual-port static RAM. This memory is accessible simultaneously by both the MC68000 core and the RISC communications processor, enabling efficient zero-copy data transfer between protocol layers. It is not cache - it is directly mapped and used for frame buffering, register shadowing, and interrupt service context storage in the MC68302EH20CR2.

How many serial communication controllers does the MC68302EH20CR2 support, and which protocols are implemented?

The MC68302EH20CR2 supports three full-duplex Serial Communication Controllers (SCCs) and two Serial Management Controllers (SMCs). Each SCC supports HDLC/SDLC, UART, Bisync, DDCMP, Totally Transparent, and V.110 protocols in hardware. The SMCs manage IDL and GCI physical layers. All protocol modes are selectable per-channel via CP register configuration in the MC68302EH20CR2.

Is the MC68302EH20CR2 pin-compatible with other MC68302 derivatives such as the MC68LC302 or MC68EN302?

No, the MC68302EH20CR2 is not pin-compatible with the MC68LC302 (100-pin TQFP) or MC68EN302 (144-pin TQFP). It uses a 132-pin TQFP package with a unique pinout optimized for its specific bus interface, SCC/SMC signal allocation, and power/ground distribution. Board-level replacement requires full schematic and layout revision for either alternative part.

What development resources are available for the MC68302EH20CR2?

Freescale provided comprehensive documentation for the MC68302EH20CR2, including the MC68302 User's Manual (M68302UM/AD), application notes on HDLC implementation and interrupt handling, and sample C and assembly code for bootloaders and protocol stacks. Third-party tools included CodeWarrior IDE support and JTAG debug probes compatible with the MC68302EH20CR2's on-chip debugging features.