Fujitsu FR81S User Manual
CHAPTER 44: 12-BIT A/D CONVERTER
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: 12-BIT A/D CONVERTER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
104
5.3.1. A/D Activation Trigger Arbitration
The A/D activation trigger arbitration is explained.
An A/D activation trigger is generated after one of activation requests from A/D activation compare
channels is selected. Three types of activation requests from individual A/D activation compare channels
are entered: software activation request, external trigger/reload timer activation request/PPG activation, and
compare-match activation request. A/D activation trigger signals are thus generated. If contention occurs
among multiple activation requests, the activation request from the lowest compare channel number takes
precedence. Activation requests that are not selected are made to wait. When the current A/D conversion
completions, arbitration restarts.
The sequence of activation arbitration priorities based on the activation factor is as follows: Compare-match
activation request > external trigger/reload timer activation request/PPG activation request > software
activation request. If two activation requests are caused by activation factors assigned the same priority, the
request from the lower activation channel number takes precedence.
If an activation factor with the same priority is encountered during A/D conversion suspension:
The request from the activation channel with the lower number is processed first.
If an activation factor with a different priority is encountered during A/D conversion suspension:
The request based on the higher-priority activation factor is processed first.
If an activation factor with a higher priority is encountered during A/D conversion:
The current conversion is suspended, and the higher-priority activation factor is processed. After this
processing completions, arbitration is performed again. The suspended activation factor is then
processed.
If an activation factor with a lower priority is encountered during A/D conversion:
After the current conversion completions, arbitration is performed again. The activation factor with the
lower priority is then processed.
If an activation factor with the same priority is encountered during A/D conversion:
After the current conversion completions, arbitration is performed again. The activation factor with the
same priority is then processed.
Figure 5-22 Activation Arbitration
Software activation
request
When compare match activation occurs (activation channel N+1) during software activation (activation channel N),
suspends software activation conversion and preferentially processes compare match activation conversion.
Restarts (re-executes) the suspended software activation conversion after the process.
Compare match
activation request
A/D conversion
During conversion(softwear)
stop
During conversion(softwear)
During conversion (compare match)
stop
When software activation occurs (activation channel N) during external trigger activation (activation channel N+1),
processes software activation conversion after completion of external trigger conversion
External trigger
activation request
Software activation
request
A/D conversion
During conversion(external trigger)
stop
During conversion(software)
stop
Activation trigger
Activation trigger
Suspends software conversion
Restarts software conversion
MB91520 Series
MN705-00010-1v0-E
1907