SSIZEx Encoding, Bit Definition | Motorola MC68340 specs

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Dual-Address Mode—This bit defines which device generates requests.

1 = If request generation is programmed to be external (REQ = 1x), the source device generates the request, and the control signals (DREQ≈, DACK≈, and DONE≈) are part of the source (read) portion of the transfer.

0 = If request generation is programmed to be external (REQ = 1x), the destination device generates the request, and the control signals (DREQ≈, DACK≈, and DONE≈) are part of the destination (write) portion of the transfer.

SAPI—Source Address Pointer Increment

1 = The SAR is incremented by 1, 2, or 4 after each transfer, according to the source size. The address that is written into the SAR points to a memory block and is incremented to complete the data transfer.

0 = The SAR is not incremented during operand transfer. The address that is written

into the SAR points to a peripheral device and is used for the complete data transfer.

DAPI—Destination Address Pointer Increment

1 = The DAR is incremented by 1, 2, or 4 after each transfer, according to the source size. The address that is written into the DAR points to a memory block and is incremented to complete the data transfer.

0 = The DAR is not incremented during operand transfer. The address that is written

into the DAR points to a peripheral device and is used for the complete data transfer.

SSIZE—Source Size Control Field

This field controls the size of the source (read) bus cycle that the DMA channel is running. Table 6-2 defines these bits.

Table 6-2. SSIZEx Encoding

Bit 9	Bit 8	Definition
0	0	Long Word*
0	1	Byte
1	0	Word
1	1	Not Used

*External logic is required to complete a long- word transfer.

6- 28MC68340 USER’S MANUALMOTOROLA

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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.

Motorola MC68340 manual SSIZEx Encoding, Bit Definition

Models: MC68340

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

Table 6-2. SSIZEx Encoding

Bit 9

Definition

MC68340 specifications