{{Infobox BSP |BSP_name = MC68340 |Manufacturer = Motorola |image = MC68340.jpg |Board_URL = |Architecture = 32-bit |CPU_model = CPU32 |RAM = 4MB |NVMEM = 32 MB Flash, 16 KB EEPROM }} The MC68340 is a high-performance 32-bit integrated processor with direct memory access (DMA), combining an enhanced M68000-compatible processor, 32-bit DMA, and other peripheral subsystems on a single integrated circuit. The MC68340 CPU32 delivers 32-bit CISC processor performance from a lower cost 16-bit memory system. The combination of peripherals offered in the MC68340 can be found in a diverse range of microprocessor-based systems. Systems requiring very high-speed block transfers of data can benefit from the MC68340.


The M68300 family of integrated processors and controllers is built on an M68000 core processor, an on-chip bus, and a selection of intelligent peripherals appropriate for a set of applications. The CPU32 is a powerful central processor with nearly the performance of the MC68020. A system integration module incorporates the external bus interface and many of the smaller circuits that typically surround a microprocessor for address decoding, wait-state insertion, interrupt prioritization, clock generation, arbitration, watchdog timing, and power-on reset timing. Each member of the M68300 family is distinguished by its selection of peripherals. Peripherals are chosen to address specific applications but are often useful in a wide variety of applications. The peripherals may be highly sophisticated timing or protocol engines that have their own processors, or they may be more traditional peripheral functions, such as UARTs and timers. Since each major function is designed in a standalone module, each module might be found in many different M68300 family parts.


290px? The CPU32 is upward source- and object-code compatible with the MC68000 and MC68010. It is downward source- and object-code compatible with the MC68020. Within the M68000 family, architectural differences are limited to the supervisory operating state. User state programs can be executed unchanged on upward-compatible devices. The major CPU32 features are as follows:

  • 32-Bit Internal Data Path and Arithmetic Hardware
  • 32-Bit Address Bus Supported by 32-Bit Calculations
  • Rich Instruction Set
  • Eight 32-Bit General-Purpose Data Registers
  • Seven 32-Bit General-Purpose Address Registers
  • Separate User and Supervisor Stack Pointers
  • Separate User and Supervisor State Address Spaces
  • Separate Program and Data Address Spaces
  • Many Data Types
  • Flexible Addressing Modes
  • Full Interrupt Processing
  • Expansion Capability= CPU32 =

The CPU32 is an M68000 family processor specially designed for use as a 32-bit core processor and for operation over the intermodule bus (IMB). Designers used the MC68020 as a model and included advances of the later M68000 family processors, resulting in an instruction execution performance of 4 MIPS (VAX-equivalent) at 25.16 MHz. The powerful and flexible M68000 architecture is the basis of the CPU32. MC68000 (including the MC68HC000 and the MC68EC000) and MC68010 user programs will run unmodified on the CPU32. The programmer can use any of the eight 32-bit data registers for fast manipulation of data and any of the eight 32-bit address registers for indexing data in memory. The CPU32 can operate on data types of single bits, binary-coded decimal (BCD) digits, and 8, 16, and 32 bits. Peripherals and data in memory can reside anywhere in the 4-Gbyte linear address space. A supervisor operating mode protects system-level resources from the more restricted user mode, allowing a true virtual environment to be developed.


The MC68340 is available as 0–16.78 MHz and 0–25.16 MHz, 0°C to +70°C and -40°C to +85°C, and 5.0 V ±5% and 3.3 V ±0.3 supply voltages (reduced frequencies at 3.3 V). Thirty-two power and ground leads minimize ground bounce and ensure proper isolation of different sections of the chip, including the clock oscillator. A 144 pins are used for signals and power. The MC68340 is available in a gull-wing ceramic quad flat pack (CQFP) with 25.6-mil (0.001-in) lead spacing or a 15 ´ 15 plastic pin grid array (PPGA) with 0.1-in pin spacing.

System Integration Module

The MC68340 SIM40 provides the external bus interface for both the CPU32 and the DMA. It also eliminates much of the glue logic that typically supports the microprocessor and its interface with the peripheral and memory system. The SIM40 provides programmable circuits to perform address decoding and chip selects, wait-state insertion, interrupt handling, clock generation, bus arbitration, watchdog timing, discrete I/O, and power-on reset timing. A boundary scan test capability is also provided.

External Bus Interface

The external bus interface (EBI) handles thetransfer of information between the internal CPU32 or DMA controller and memory, peripherals, or other processing elements in the external address space. Based on the MC68030 bus, the external bus provides up to 32 address lines and 16 data lines. Address extensions identify each bus cycle as CPU32 or DMA initiated, supervisor or user privilege level, and instruction or data access. The data bus allows dynamic sizing for 8- or 16-bit bus accesses (plus 32 bits for DMA). Synchronous transfers from the CPU32 or the DMA can be made in as little as two clock cycles.

Clock Synthesizer

The clock synthesizer generates the clock signals used by all internal operations as well as a clock output used by external devices. The clock synthesizer can operate with an inexpensive 32768-Hz watch crystal or an external oscillator for reference, using an internal phase-locked loop and voltage-controlled oscillator. At any time, software can select clock frequencies from 131 kHz to 16.78 MHz or 25.16 MHz, favoring either low power consumption or high performance. Alternately, an external clock can drive the clock signal directly at the operating frequency. With its fully static HCMOS design, it is possible to completely stop the system clock without losing the contents of the internal registers.

External links

Last modified on Nov 29, 2010 at 10:39:23 PM Last modified on Nov 29, 2010, 10:39:23 PM