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CHAPTER 14 8/10-BIT A/D CONVERTER
14.7
A/D Conversion Data Protection Function
When the A/D conversion is executed in the interrupt enable status, the conversion data
protection function works.
■ A/D Conversion Data Protection Function
The A/D converter only has one data register for storing conversion data. For this reason, when performing
A/D conversion, after conversion is completed, the data stored in the data register is rewritten. Therefore,
when the converted data transfer to the memory is delayed, a part of previous data may be lost. To get
around this, when interrupts are enabled (INTE = 1), the data-protection feature works as described below.
When conversion data is stored in the A/D data register (ADCD), the INT bit of the A/D control status
register (ADCS) is set to "1". While the INT bit is "1", conversion data will not be stored to ADCD after
the next conversion ends. The PAUS bit is set, and A/D conversion becomes suspended. While suspended,
the value immediately prior is retained. In order to cancel the suspend, clear the INT bit. After the
suspended status is cleared, the conversion data that had been maintained is stored in ADCD, and the next
operation is performed.
Notes:
• The converted data protection function operates only in the interrupt enabled (ADCS: INTE=1)
status.
• When the conversion is restarted during the suspension, the waiting data are destroyed.
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