Printer DMA Transfer Mode Switching for High-Speed Data Handling
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Solution Overview
Problem
Existing printers experience a time lag between detecting the header of a print image command and initiating DMA transfer, resulting in part of the data payload being stored in the receive buffer and processed in normal transfer mode, which slows down the entire data transfer process.
Innovation Solution
A printer system with an interrupt evaluation unit that determines if received data is a print image command header, pauses data transmission, and switches to DMA transfer mode upon confirmation, allowing direct data transfer to the print buffer without storing in the receive buffer, thereby preventing data payload storage during the time lag and enabling high-speed data transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the printer uses normal transfer mode to store received data in the receive buffer, then data can be processed sequentially, but data transfer speed is reduced
Solution Approach 1:
The patent dynamically switches between normal transfer mode and DMA transfer mode based on the type of data being received. The mode selector changes the data transfer mode from normal transfer mode to DMA transfer mode when a print image command header is detected, and switches back to normal transfer mode for other data types. This dynamic adaptation resolves the contradiction by using the faster DMA mode only when appropriate, while maintaining the simpler normal mode for other cases.
2Productivity
If the printer switches to DMA transfer mode upon detecting a print image command header, then data transfer is accelerated, but part of the data payload is stored in the receive buffer during the time lag between detection and mode switching
Solution Approach 1:
The patent applies preliminary action by pausing data transmission from the host device immediately when a print image command header is detected in the receive buffer, before the mode switching is completed. The data transmission-stop unit pauses data transmission by the host device if the header of a print image command is detected in the receive interrupt process. This prevents additional data from being stored in the receive buffer during the mode transition, ensuring that the entire data payload can be transferred via DMA without interruption.
3Speed
If the printer pauses data transmission when a print image command header is detected, then the entire data payload can be transferred by DMA, but data transmission is interrupted for non-DMA commands
Solution Approach 1:
The patent dynamically controls data transmission based on the command type detected. The cancel transmission-stop unit cancels the pause of data transmission by the host device if the command interpreter determines the data is a header of a print image command that can be transferred by DMA. For other data types, the pause remains in effect. This dynamic control ensures that data transmission is only paused when necessary for DMA transfer, maintaining reliability for non-DMA commands while achieving high-speed transfer for eligible image commands.
Data Source
AI summary
Whether received data is the header of a print image command is determined in a receive interrupt process. If the received data is the header of a print image command, data transmission is paused. Whether the received data is a header of a print image command that can be transferred by DMA is then determined in a command task. If the received data is a header of a print image command that can be transferred by DMA, a DMA transfer mode is entered and the data transmission pause is cancelled, and the received data is transferred in the DMA transfer mode to a print buffer 42 by DMA.