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ATSAM4S-XPLD
969
SAM4S [DATASHEET]
11100E–ATARM–24-Jul-13
40.6
Functional Description
40.6.1 ACC Description
The Analog Comparator Controller mainly controls the analog comparator settings. There is also post processing of the
analog comparator output.
analog comparator output.
The output of the analog comparator is masked for the time the output may be invalid. This situation is encountered as
soon as the analog comparator settings are modified.
soon as the analog comparator settings are modified.
A comparison flag is triggered by an event on the output of the analog comparator and an interrupt can be generated
accordingly. The event on the analog comparator output can be selected among falling edge, rising edge or any edge.
accordingly. The event on the analog comparator output can be selected among falling edge, rising edge or any edge.
The registers for programming are listed in
.
40.6.2 Analog Settings
The user can select the input hysteresis and configure high-speed or low-speed options.
shortest propagation delay/highest current consumption
longest propagation delay/lowest current consumption
40.6.3 Write Protection System
In order to provide security to the Analog Comparator Controller, a write protection system has been implemented.
The write protection mode prevents writing
enabled and one of the protected registers is written, the register write request is canceled.
Due to the nature of the write protection feature, enabling and disabling the write protection mode requires a security
code. Thus when enabling or disabling the write protection mode, the WPKEY field of the ACC_WPMR register must be
filled with the “ACC” ASCII code (corresponding to 0x414343), otherwise the register write will be canceled.
code. Thus when enabling or disabling the write protection mode, the WPKEY field of the ACC_WPMR register must be
filled with the “ACC” ASCII code (corresponding to 0x414343), otherwise the register write will be canceled.
40.6.4 Automatic Output Masking Period
As soon as the analog comparator settings change, the output is invalid for a duration depending on ISEL current.
A masking period is automatically triggered as soon as a write access is performed on ACC_MR or ACC_ACR registers
(whatever the register data content).
(whatever the register data content).
When ISEL = 0, the mask period is 8*tMCK, else 128*tMCK.
The masking period is reported by reading a negative value (bit 31 set) on ACC_ISR register
40.6.5 Fault Mode
The FAULT output can be used to propagate a comparison match and act immediately via combinatorial logic by using
the FAULT output which is directly connected to the FAULT input of the PWM.
the FAULT output which is directly connected to the FAULT input of the PWM.
The source of the FAULT output can be configured to be either a combinational value derived from the analog
comparator output or the MCK resynchronized value (Refer to
comparator output or the MCK resynchronized value (Refer to