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16.6 Operation of the 8/10-Bit A/D Converter
16.6.2 A/D Conversion Data Protection Function
When A/D conversion is performed in the interrupt enabled state, the conversion data
protection function operates.
s A/D Conversion Data Protection Function
The 8/10-bit A/D converter has only one data register for conversion data storage. Thus, when
A/D conversion is performed, the data stored in the data register is rewritten when the
conversion is completed. In continuous conversion mode, if conversion data is transferred to
memory too late, part of the stored data will be missing.
As measures against such data omission, the data protection function works as shown below if
an interrupt request is enabled (ADCS1: INTE="1").
r Data protection function when EI2OS is not used
When conversion data is stored in the A/D data register (ADCR0/ADCR1), the interrupt request
flag bit (INT) of the A/D control status register 1 (ADCS1) is set to "1" and the A/D conversion is
halted.
The A/D conversion is restarted after transferring the A/D data register (ADCR0/
ADCR1) values to memory in the interrupt routine and the interrupt request flag bit (INT) is
cleared to "0".
r Data protection function when EI2OS is used
In continuous conversion mode, the pause flag bit (PAUS) of the A/D control status register 1
(ADCS1) is set to "1" if EI2OS is used and A/D conversion is completed, but the transfer of the
last piece of data to memory is not completed so that the A/D conversion is halted and
conversion data is not stored in the A/D data register (ADCR0/ADCR1). When the transfer of
the last piece of data to memory is completed, the pause flag bit (PAUS) is cleared to "0" and
the A/D conversion is restarted.