Chapter 10 Analog-to-Digital Converter (ADC12B_LBA_V1)
S12ZVHY/S12ZVHL Family Reference Manual Rev. 1.05
408
Freescale Semiconductor
10.5.3.2.6
Conversion flow control in case of conversion sequence control bit overrun
scenarios
Restart Request Overrun:
If a legal Restart Request is detected and no Restart Event is in progress, the RSTA bit is set due to the
request. The set RSTA bit indicates that a Restart Request was detected and the Restart Event is in process.
In case further Restart Requests occur while the RSTA bit is set, this is defined a overrun situation. This
scenario is likely to occur when bit STR_SEQA is set or when a Restart Event causes a Sequence Abort
Event. The request overrun is captured in a background register that always stores the last detected overrun
request. Hence if the overrun situation occurs more than once while a Restart Event is in progress, only
the latest overrun request is pending. When the RSTA bit is cleared, the latest overrun request is processed
and RSTA is set again one cycle later.
LoadOK Overrun:
Simultaneously at any Restart Request overrun situation the LoadOK input is evaluated and the status is
captured in a background register which is alternated anytime a Restart Request Overrun occurs while
Load OK Request is asserted. The Load OK background register is cleared as soon as the pending Restart
Request gets processed.
Trigger Overrun:
If a Trigger occurs whilst bit TRIG is already set, this is defined as a Trigger overrun situation and causes
the ADC to cease conversion at the next conversion boundary and to set bit TRIG_EIF. A overrun is also
detected if the Trigger Event occurs automatically generated by hardware in “Trigger Mode” due to a
Restart Event and simultaneously a Trigger Event is generated via data bus or internal interface. In this
case the ADC ceases operation before conversion begins to sample. In “Trigger Mode” a Restart Request
Overrun does not cause a Trigger Overrun (bit TRIG_EIF not set).
Sequence Abort Request Overrun:
If a Sequence Abort Request occurs whilst bit SEQA is already set, this is defined as a Sequence Abort
Request Overrun situation and the overrun request is ignored.
