Datasheet

Section 19 A/D Converter
Rev. 2.00 Sep. 28, 2009 Page 635 of 870
REJ09B0429-0200
19.5 Interrupt Source
The A/D converter generates an A/D conversion end interrupt (ADI) at the end of A/D conversion.
Setting the ADIE bit to 1 enables ADI interrupt requests while the ADF bit in ADCSR is set to 1
after A/D conversion ends. The ADI interrupt can be used to activate the DTC. Reading the
converted data by the DTC activated by the ADI interrupt allows consecutive conversion to be
performed without software overhead.
Table 19.5 A/D Converter Interrupt Source
Name Interrupt Source Interrupt Flag DTC Activation
ADI A/D conversion end ADF Possible
19.6 A/D Conversion Accuracy Definitions
This LSI’s A/D conversion accuracy definitions are given below.
• Resolution
The number of A/D converter digital output codes
• Quantization error
The deviation inherent in the A/D converter, given by 1/2 LSB (see figure19.6).
• Offset error
The deviation of the analog input voltage value from the ideal A/D conversion characteristic
when the digital output changes from the minimum voltage value B'00 0000 0000 (H'000) to
B'00 0000 0001 (H'001) (see figure 19.7).
• Full-scale error
The deviation of the analog input voltage value from the ideal A/D conversion characteristic
when the digital output changes from B'11 1111 1110 (H'3FE) to B'11 1111 1111 (H'3FF) (see
figure 19.7).
• Nonlinearity error
The error with respect to the ideal A/D conversion characteristics between the zero voltage and
the full-scale voltage. Does not include the offset error, full-scale error, or quantization error
(see figure 19.7).
• Absolute accuracy
The deviation between the digital value and the analog input value. Includes the offset error,
full-scale error, quantization error, and nonlinearity error.