HD6417320 RENESAS [Renesas Technology Corp], HD6417320 Datasheet - Page 1008

• Manufacturer Part Number: HD6417320
• Description: Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 27
27.7
27.7.1
(1)
Problem: Even though the ADCSR.ADF bit has been read as 1 and 0 was then written to the ADF
bit, the ADF bit has not been cleared to 0.
Condition: This problem arises when reading of the ADF bit coincides with setting of the bit to 1
upon the end of A/D conversion.
Avoiding the Problem: Follow any of procedures (a), (b), or (c) below.
(2)
Problem: A/D conversion in scan mode is not stopped by clearing the ADCSR.ADST bit (to 0).
Condition: This problem arises when 0 is written to the ADST bit in ADCSR to stop A/D
conversion while A/D conversion in scan mode is in progress.
Avoiding the Problem: Place the ADC in module standby state after clearing the ADST bit (to 0).
Placing the ADC in the module standby state initializes the ADC and stops A/D conversion. When
further A/D conversion is required, restart A/D conversion after releasing the ADC from the
module standby state.
(3)
Problem: An incorrect superfluous DMA transfer is included before DMA transfer of the correct
result of A/D conversion.
Rev. 3.00
REJ09B0033-0300
(a) Ensure that setting of the ADF bit to 1 upon the end of A/D conversion does not coincide
(b) If the ADF bit has not been cleared, repeat the operation of reading it as 1 and then
(c) Initialize the ADC and clear the ADF bit by placing the ADC in the module standby state.
Notes on Clearing the ADF Bit in the ADCSR Register
Notes on A/D Conversion in Scan Mode
Notes on Transferring the Result of A/D Conversion by the DMAC
with reading of the ADF bit. For example, read the ADF bit as 1 and then write 0 to the
bit during processing of the A/D conversion end interrupt (ADI) that is generated at the
end of A/D conversion (when the ADF is set to 1).
writing 0 to it.
Usage Notes
Notes on A/D Conversion
Jan. 18, 2008
A/D Converter
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