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Motorola MC68340 manual NON-IEEE 1149.1 Operation

Models: MC68340

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Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

The MC68340 includes on-chip circuitry to detect the initial application of power to the device. Power-on reset (POR), the output of this circuitry, is used to reset both the system and IEEE 1149.1 logic. The purpose for applying POR to the IEEE 1149.1 circuitry is to avoid the possibility of bus contention during power-on. The time required to complete device power-on is power-supply dependent. However, the IEEE 1149.1 TAP controller remains in the test-logic-reset state while POR is asserted. The TAP controller does not respond to user commands until POR is negated.

The MC68340 features a low-power stop mode that uses a CPU instruction called LPSTOP. The interaction of the IEEE 1149.1 interface with LPSTOP mode is as follows:

1.Leaving the TAP controller test-logic-reset state negates the ability to achieve minimal power consumption, but does not otherwise affect device functionality.

2.The TCK input is not blocked in LPSTOP mode. To consume minimal power, the TCK input should be externally connected to VCC or ground.

3.The TMS and TDI pins include on-chip pullup resistors. In LPSTOP mode, these two

pins should remain either unconnected or connected to VCC to achieve minimal power consumption.

9.6NON-IEEE 1149.1 OPERATION

In non-IEEE 1149.1 operation, there are two constraints. First, the TCK input does not include an internal pullup resistor and should be pulled up externally to preclude mid-level inputs. The second constraint is to ensure that the IEEE 1149.1 test logic is kept transparent to the system logic by forcing the TAP controller into the test-logic-reset state, using either of two methods. During power-on, POR forces the TAP controller into this state. Alternatively, sampling TMS as a logic one for five consecutive TCK rising edges also forces the TAP controller into this state. If TMS either remains unconnected or is connected to VCC, then the TAP controller cannot leave the test-logic-reset state, regardless of the state of TCK.

9- 12MC68340 USER’S MANUALMOTOROLA

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Motorola MC68340 manual NON-IEEE 1149.1 Operation
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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.