SH7144 Datasheet, PDF (515/773 Pages) Renesas Technology Corp – Hitachi SuperH RISC engine

15.5 Interrupt Sources and DTC, DMAC Transfer Requests
The A/D converter generates an A/D conversion end interrupt (ADI) upon the completion of A/D
conversion. ADI interrupt requests are enabled when the ADIE bit is set to 1 while the ADF bit in
ADCSR is set to 1 after A/D conversion is completed. The data transfer controller (DTC) or the
direct memory access controller (DMAC) can be activated by an ADI interrupt. Having the
converted data read by the DTC or the DMAC in response to an ADI interrupt enables continuous
conversion to be achieved without imposing a load on software.
When the DTC or the DMAC is activated by an ADI interrupt, the ADF bit in ADCSR is
automatically cleared when data is transferred by the DTC or the DMAC.
Table 15.5 A/D Converter Interrupt Source
Name Interrupt Source
Interrupt Source Flag DTC Activation DMAC Activation
ADI0 A/D0 conversion completed ADF in ADCSR_0
Possible
Impossible
ADI1 A/D1 conversion completed ADF in ADCSR_1
Possible
Possible
15.6 Definitions of A/D Conversion Accuracy
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 figure 15.4).
• 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'0000000000 (H'00) to
B'0000000001 (H'01) (see figure 15.5).
• 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'1111111110 (H'3FE) to B'1111111111 (H'3FF) (see
figure 15.5).
• Nonlinearity error
The error with respect to the ideal A/D conversion characteristic between zero voltage and full-
scale voltage. Does not include offset error, full-scale error, or quantization error (see figure
15.5).
• Absolute accuracy
The deviation between the digital value and the analog input value. Includes offset error, full-
scale error, quantization error, and nonlinearity error.
Rev. 2.0, 09/02, page 475 of 732