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25.3.12 External Override Interface
The ACMP can be controlled by an external module, for instance LESENSE. In this mode, the external module will take control of the
positive input mux control signal, which is normally controlled by ACMP_INPUTSEL_POSSEL. Only the APORTs are selectable for the
positive input mux in this mode. Which APORT(s) used is configured in ACMP_EXTIFCTRL_APORTSEL.
ACMP_EXTIFCTRL_APORTSEL also controls the base value for the positive input mux control signal. The external module will be able
to add an offset to this base. The resulting mux configuration can be calculated using
Figure 25.6 POSSEL in External Override Mode
. The external module controls EXT_OFFSET, while EXT_BASE is controlled by ACMP. See register description of
ACMP_EXTIFCTRL_APORTSEL to see values of EXT_BASE.
POSSEL = EX EXT_OFFSET
Figure 25.6. POSSEL in External Override Mode
Note:
If only one APORT in a pair is used, the external module needs to be programmed to only use the channels that the ACMP has
control of.
The external module is also able to override DIVVA and DIVVB in ACMP_HYSTERESIS0/HYSTERESIS1. This needs to be enabled in
the external module. If the external module does not override DIVVA/DIVVB, the configuration in ACMP_HYSTERESIS0/
HYSTERESIS1 will be used.
To enable the external override interface these steps must be performed:
• Configure the parts of the ACMP that will not be overridden, i.e. everything except ACMP_INPUTSEL_POSSEL and possibly
ACMP_HYSTERESIS0/HYSTERESIS1. Make sure ACMP_CTRL_EN is set.
• Configure and enable the external override interface in ACMP_EXTIFCTRL.
• Check for APORT conflicts in ACMP_APORTCONFLICT.
• Wait for ACMP_STATUS_EXTIFACT to go high, indicating that the interface is ready to use.
25.4 Register Map
The offset register address is relative to the registers base address.
Offset
Name
Type
Description
RW
RW
R
R
W1
(R)W1
RW
R
R
APORT Conflict Status Register
RW
RW
RW
I/O Routing Pine Enable Register
RW
RW
External Override Interface Control
Reference Manual
ACMP - Analog Comparator
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