TC1796
Peripheral Units (Vol. 2 of 2)
Analog-to-Digital Converter (ADC)
User’s Manual 25-10 V2.0, 2007-07
ADC, V2.0
If “Timer” is the arbitration winner, a conversion is started for the conversion request
within register TCRP with the highest channel number. Starting a conversion causes the
conversion request bit in register TCRP to be cleared by the arbiter. If a currently running
timer initiated conversion is cancelled, the arbiter sets the corresponding conversion
request bit in registers TCRP for this channel. If all pending conversion requests are
processed, the arbiter clears the arbitration participation flag AP.TP. The contents of
register TCRP can be cleared globally under software control by clearing the timer
arbitration participation flag AP.TP.
The arbitration-lock mechanism provides the means to start timer triggered conversion
requests without being delayed by a currently running conversion. Figure 25-6 shows
this method in detail.
Figure 25-6 Arbitration Lock Mechanism
The arbitration must be locked before the timer is 0 in order to ensure that the running
conversion has been finished and no new conversion will be started in the meantime.
When the arbitration is locked, lower prioritized conversion request source than the
“Timer” are blocked from performing requested conversions.
Ch 'x' by TimerChannel 'n' by Source 'y'
Waiting for timer
MCT06009
t
TIMER
f
TIMER
Execute pending requests Execute pending req.
Conversion
Requests
Scan
Timer
Scan
Timer
Scan
Timer
Scan
Timer
Scan
Timer Scan ScanScanScanScan
Arbitration
Conversion Idle
Timer Period
Reload Value
Arbitration Lock
Boundary
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