Precautions On Using A-D Converters - Mitsubishi Electric M32R Series User Manual

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11.4 Precautions on Using A-D Converters

• Forcible termination during scan operation
If A-D conversion is halted by setting the A-D conversion stop bit (AD0CSTP, AD1CSTP) to 1
during scan mode operation and you read the content of the A-D data register for the channel in
which conversion was in progress, it shows the last conversion result that had been transferred to
the A-D data register before the conversion was forcibly terminated.
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• ADTRG signal and input/output port
If you selected the ADTRG signal for an A-D conversion start trigger, do not use the ADTRG pin
as an input/output port (P67).
• Modification of A-D converter related registers
If you want to change the contents of the A-D Conversion Interrupt Control Register, each Single
and Scan Mode Register, or A-D Successive Approximation Register, except for the A-D
conversion stop bit, do your change while A-D conversion is inactive, or be sure to restart A-D
conversion after you changed the register contents. If the contents of these registers are
changed in the middle of A-D conversion, the conversion results cannot be guaranteed.
• Handling of analog input signals
The A-D converters included in the 32170 do not have a sample-and-hold circuit. Therefore,
make sure the analog input levels are fixed during A-D conversion.
• A-D conversion completion bit readout timing
If you want to read the A-D conversion completion bit (Single Mode Register 0's D5 bit or Scan
Mode Register 0's D5 bit) immediately after A-D conversion has started, be sure to adjust the
timing one clock cycle by, for example, inserting a NOP instruction before you read.
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11.4 Precautions on Using A-D Converters
A-D CONVERTERS
Ver.0.10