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Motorola manual MC68340 Initialization Sequence, Startup, 2 SIM40 Module Configuration

Models: MC68340

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Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

4.4 MC68340 INITIALIZATION SEQUENCE

The following paragraphs discuss a suggested method for initializing the MC68340 after power-up.

4.4.1 Startup

RESET is asserted by the MC68340 during the time in which VCC is ramping up, the VCO is locking onto the frequency, and the MC68340 is going through the reset operation. After RESET is negated, four bus cycles are run, with global CS0 being asserted to fetch the 32-bit supervisor stack pointer (SSP) and the 32-bit program counter (PC) from the boot ROM. Until programmed differently, CS0 is a global, 16-bit-wide, three-wait-state chip select. CS0 can be programmed to continue decode for a range of addresses after the V-bit is set, provided the desired address range is first loaded into the CS0 base address register. After the V-bit is set for CS0, global chip select can only be restarted with a system reset.

After the SSP and the PC are fetched, the module base address register (MBAR) should be initialized, and the MBAR V-bit should be set (CPU space address $0003FF00) with the desired base address for the internal modules.

4.4.2 SIM40 Module Configuration

The order of the following SIM40 register initializations is not important; however, time can be saved by initializing the SYNCR first to quickly increase to the desired processor operating frequency. The module base address register must be initialized prior to any of following steps.

Clock Synthesizer Control Register (SYNCR):

•Set frequency control bits (W, X, Y) to specify frequency.

•Select action taken during loss of crystal (RSTEN bit): activate a system reset or operate in limp mode.

•Select system clock and CLKOUT during LPSTOP (STSIM and STEXT bits).

Module Configuration Register (MCR)

•If using the software watchdog, periodic interrupt timer, and/or the bus monitor, select action taken when FREEZE is asserted (FRZx bits).

•Select port B configuration (FIRQ bit). Note that this bit is used in combination with the bits in the PPARB to program the function of the port B pins.

•Select the access privilege for the supervisor/user registers (SUPV bit).

•Select the interrupt arbitration level for the SIM40 (IARBx bits).

Autovector Register (AVR)

• Select the desired external interrupt levels for internal autovectoring.

4- 36MC68340 USER’S MANUALMOTOROLA

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Motorola manual MC68340 Initialization Sequence, Startup, 2 SIM40 Module Configuration
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MC68340 specifications

The Motorola MC68340 is a highly integrated microprocessor that was introduced in the early 1990s. It belongs to the 68000 family of microprocessors and is designed to cater to the demands of embedded systems, particularly in telecommunications and networking applications. This chip represents a significant evolution in microprocessor technology by combining a microprocessor core with additional peripherals on a single chip, making it an attractive solution for engineers looking to design compact and efficient systems.

One of the key features of the MC68340 is its 32-bit architecture, which allows for significant processing power and data handling capabilities. This architecture enables the processor to handle larger data sizes and perform more complex calculations compared to its 16-bit predecessors. The MC68340 operates at clock speeds typically ranging from 16 MHz to 25 MHz. Its dual instruction pipeline enhances throughput, allowing for simultaneous instruction fetches and executions, which significantly boosts performance.

A notable characteristic of the MC68340 is the inclusion of integrated peripherals, which help reduce the overall component count in a system. Key integrated components include a memory management unit (MMU), a direct memory access (DMA) controller, and various communication interfaces such as serial ports. The memory management capabilities enhance the processor's ability to manage memory resources efficiently, enabling it to support multitasking environments commonly found in modern computing.

In terms of connectivity, the MC68340 features connections for both synchronous and asynchronous serial communication, making it well-suited for networking tasks. The processor supports a range of bus standards, including address and data buses, which facilitate seamless interaction with peripheral devices.

Another important aspect of the MC68340 is its flexibility. The processor supports multiple operating modes, including multiple CPU configurations and compatibility with the Motorola 68000 family, allowing for easier integration into existing systems.

Moreover, the MC68340 boasts low power consumption compared to many of its contemporaries, making it an excellent choice for battery-operated applications, enhancing its appeal in sectors like telecommunications, industrial control, and automotive systems. Its combination of performance, integration, versatility, and efficiency has secured the MC68340 a reputable position in the annals of embedded systems technology, proving to be a valuable asset for developers and engineers alike.