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Article: DMA eases CPU's workload for waveform generation.(design ideas: READERS SOLVE DESIGN PROBLEMS)
- Article from:
- EDN
- Article date:
- December 5, 2005
- Author:
CopyrightCOPYRIGHT 2005 Reed Business Information, Inc. (US). This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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To generate analog voltages and waveforms, embedded systems often require one or more embedded or external DACs. To produce an analog voltage, the CPU must write the desired output value to the DAC at the appropriate time, a task that a timer-generated interrupt applied to the CPU usually initiates. In applications in which the DAC generates a periodic waveform, the CPU reads the next value from the table, sends it to the DAC, increments a table pointer, and checks for table boundaries to determine when to reset the table pointer.
Writing the periodic values to the DAC to maintain the output waveform requires CPU overhead, which varies depending on the data ...