Rev. 1.00
106
��ne ��� �01�
Rev. 1.00
10�
��ne ��� �01�
HT66FM5440
Brushless DC Motor A/D Flash MCU
HT66FM5440
Brushless DC Motor A/D Flash MCU
The following are some important notes for simutaniously using both trigger methods:
• The analog channel to be converted by the ADSTR triggered A/D conversion is determined by
the ACS bit field.
• The analog channels to be converted by the DLSTR triggered A/D conversion is determined by the
ADCH_SEL and ADISn bit fields. Up to four channels can be converted in one DLSTR triggered
A/D conversion.
• The DLSTR triggered A/D conversion has a higher priority than the ADSTR triggered A/D conversion
thus the former can interrupt the later. If this happens the ongoing ADSTR triggered A/D conversion
will be abandoned and the ADRE bit will be set high by hardware to inform the system that the
current result in the ADRH and ADRL registers is invalid.
• When entering the DLSTR trigger mode, the A/D converter will automatically switch to the first
channel defined by the ADIS0 bie field. The system will wait for a delay time defined by ADDL
and start to convert the first channel. Note that only before the first channel conversion the ADDL
delay time is required.
• During each channel conversion the system will simutaniously check whether the current channel
is the last one. If no the converter will switch to the next channel. If yes the converter will switch
back to the channel defined by the ACS bit field.
• The converted result of channel defined by ADISn bit field is strored in the ISRHn and ISRLn
registers.
• When the last channel conversion has been finished, the ISEOCB bit will be set high and the
ISAEOCF interrupt will be generated.
• When switching back to the ACS defined channel, the converter will not re-sample the interrupted
A/D conversion channel. If users need to re-sample the input channel, set the ADSTR bit from
low to high and low again.
Programming Considerations
During microcontroller operations where the A/D converter is not being used, the A/D internal
circuitry can be switched off to reduce power consumption, by
setting
bit AD
OFF
high in the
ADCR0 register. When this happens, the internal A/D converter circuits will not consume power
irrespective of what analog voltage is applied to their input lines. If the A/D converter input lines are
used as normal I/Os, then care must be taken as if the input voltage is not at a valid logic level, then
this may lead to some increase in power consumption.
A/D Conversion Function
As the device contains a 12-bit A/D converter, its full-scale converted digitised value is equal to
FFFH. Since the full-scale analog input value is equal to AV
DD
, this gives a single bit analog input
value of AV
DD
divided by 4096.
1 LSB=AV
DD
÷ 4096
The A/D Converter input voltage value can be calculated using the following equation:
A/D input voltage=A/D output digital value × AV
DD
÷ 4096
The diagram shows the ideal transfer function between the analog input value and the digitised
output value for the A/D converter. Except for the digitised zero value, the subsequent digitised
values will change at a point 0.5 LSB below where they would change without the offset, and the
last full scale digitised value will change at a point 1.5 LSB below the AV
DD
level. Note that for
the 10-bit A/D conversion, 1 LSB= AV
DD
÷ 1024.