DS80CH11 Datasheet, PDF (49/88 Pages) Dallas Semiconductor – System Energy Manager

DS80CH11
7.8 A/D SPECIAL FUNCTION REGISTERS
The following is a description of the Special Function
Registers used to control the on–chip A/D converter.
7.8.1 ADCON1 – A/D Control Register 1
ADCON1; SFR ADDR.=0B2H
BIT 7
BIT 6
BIT 5
STRT/
BSY
EOC
CONT/
SS
BIT 4
ADEX
BIT 3
WCQ
BIT 2
WCM
BIT 1
ADON
BIT 0
WCIO
Read/Write Access: (Read at any time, See individual bit description for write operation)
Initialization: 00h on any type of reset
STRT/BSY – Start/Busy.
Setting this bit to a 1 from a 0 condition will initiate an A/D
conversion. The bit will then remain set for the duration
of the conversion, regardless of any attempt to write it to
0. Thus, the bit serves as a busy flag as well. When a
conversion is complete, the A/D hardware will clear this
bit to 0.
EOC – End of Conversion.
The A/D will set this bit to a 1 when a conversion is com-
plete. EOC also serves the function of an interrupt flag
which may be qualified via the WCQ bit described
below.
CONT/SS – Continuous/Single Shot.
When set to a 1, the A/D will repeatedly run conversions
without software intervention once a conversion is initi-
ated. When cleared to a 0, the A/D will perform the
requested conversion then halt. Setting the bit from a 1
to a 0 (taking it out of continuous mode) will cause the
converter to halt when the current conversion is com-
pleted.
ADEX – A/D External Start.
When this bit is set to a 1, an A/D can be initiated by a
falling edge detected on an external pin. When set to a
0, the external pin has no effect. When a pin is used to
initiate a conversion, the A/D will write a 1 to the STRT/
BSY bit to indicate that a conversion has started. When
ADEX = 1, the STRT bit can still be used.
WCQ – Window Comparator Qualifier.
Setting this bit to a 1 enables the window comparator
qualifier function. When WCQ = 1, an interrupt can
occur only when EOC and WCM are both set to a 1 at the
end of a conversion. When cleared to a 0, an interrupt
can result each time that EOC is set at the end of any
conversion.
WCM – Window Comparator Match.
At the end of conversion, WCM is updated. WCM will be
set when the window comparator detects an A/D result
that matches the selected criteria. If the A/D result does
not match the criteria for the window as specified in the
WINHI and WINLO limit registers as well as the WCIO,
WCM will not be set.
ADON – A/D ON.
Setting this bit to a 1 applies power to the analog circuit
functions, and must be set in order to perform an A/D
conversion. The A/D requires a warm up period of t_AD
when setting this bit from a 0 to a 1 condition before a
proper conversion can be performed. In order to assure
a very low power STOP mode or to save power in other
states, this bit should be cleared to 0. Clearing ADON to
0 will abort any conversion in progress and will reset
STRT/BSY to a 0.
WCIO – Window Comparator Inside /
Outside.
When set to a 1, the window comparator looks for A/D
results that are outside of the window bounded by the
WINHI and WINLO limits. When set to a 0, the
comparator looks for A/D results that are inside of the
window bounded by WINHI and WINLO.
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