Fujitsu FR81S Manual De Usuario
CHAPTER 44: 12-BIT A/D CONVERTER
2. Features
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: 12-BIT A/D CONVERTER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
7
2.2. Function of A/D Activation Arbitration
The function of A/D activation arbitration is explained.
A/D activation arbitration is provided for each 12-bit A/D converter unit. Please refer to "Channel
allocation of each unit" for the allocation to A/D activation arbitration 0 and 1 of each A/D activation
channel.
The A/D activation arbitration consists of arbitration circuit, an A/D activation trigger generation
section, and an analog channel number select section.
Activation requests from A/D activation compare is arbitrated and the activation triggers, A/D
conversion cancel signals, and analog channel numbers are generated.
An activation trigger is generated for one selected activation request from an A/D activation compare
channel. If a contention occurs between activation requests from A/D activation compare channels, A/D
activation arbitration uses priority control. The priority order is as follows: "Lower activation channel
numbers are assigned higher priorities (priority control based on channel numbers)" or "Compare match
> external trigger/reload timer/PPG activation by activation request > software activation (priority
control based on activation factors)". Activation requests that are not selected are made to wait. When
the current A/D conversion completions, arbitration restarts.
Priority control based on activation factors is also performed during A/D conversion. In this case, the
current conversion is suspended and the activation factor assigned a higher priority is serviced. The
suspended activation factor will be activated again after the higher-priority conversion is processed if
the re-arbitration process does not find a lower channel number of a higher-priority activation factor.
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 completion, 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.
A conversion cancel signal is generated to force the current conversion processing to termination when
the activation factor that is in process of conversion becomes inactive and there is no other active
activation factor.
For the analog channel number, the activation request analog number entered from the activation
channel of the activation request arbitration result is selected.
MB91520 Series
MN705-00010-1v0-E
1810