Channel Status Register CSR, CSR1, CSR2

Freescale Semiconductor, Inc.

S/D—Single-/Dual-Address Transfer

1 = The DMA channel runs single-address transfers from a peripheral to memory or from memory to a peripheral. The destination holding register is not used for these transfers because the data is transferred directly into the destination location. The MC68340 on-chip peripherals do not support single-address transfers.

0 = The DMA channel runs dual-address transfers.

STR—Start

This bit is cleared by a hardware/software reset, writing a logic zero, or setting one of the following CSR bits: DONE, BES, BED, CONF, or BRKP. The STR bit cannot be set when the CSR IRQ bit is set. The DMA channel cannot be started until the CSR DONE, BES, BED, CONF, and BRKP bits are cleared.

Internal Request Mode:

1 = The DMA transfer starts as soon as this bit is set.

0 = The DMA transfer can be stopped by clearing this bit.

External Request Mode:

1 = Setting this bit allows the DMA to start the transfer when a DREQ≈ input is received from an external device.

0 = The DMA transfer can be stopped by clearing this bit.

NOTE

If any fields in the CCR are modified while the channel is active, that change is effective immediately. To avoid any problems with changing the setup for the DMA channel, a zero should be written to the STR bit in the CCR to halt the DMA channel at the end of the current bus cycle.

6.7.4 Channel Status Register (CSR)

The CSR contains the channel status information. This register is accessible in either supervisor or user space. The CSR can always be read or written to when the DMA module is enabled (i.e., the STP bit in the MCR is cleared).

CSR1, CSR2						$78A, $7AA
7	6	5	4	3	2	1	0
IRQ	DONE	BES	BED	CONF	BRKP	0	0
RESET
0	0	0	0	0	0	0	0

Supervisor/User

6- 30MC68340 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 Channel Status Register CSR, CSR1, CSR2

Models: MC68340

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

6.7.4 Channel Status Register (CSR)

CSR1, CSR2

6- 30MC68340 USER’S MANUALMOTOROLA

MC68340 specifications