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8.3
Activation Source and Priority
The RFU operates upon a request from the peripheral modules regarding it as an activation source.
In SCI, the request from the peripheral modules is an event that indicates 1-byte data transfer
completion, such as setting the TDRE and RDRF bits. However, in USB, the request from the
peripheral modules is an internal event that cannot be referenced by a CPU instruction. A total of
14 ID numbers have been assigned to the request from the peripheral modules. A peripheral
module to which an ID number has not been assigned cannot use the RFU. Table 8.2 summarizes
the correspondence between the ID numbers and activation sources.
When the RFU accepts multiple activation sources simultaneously, the RFU selects the ID with
the highest priority. The ID is classified into two groups, and the priority inter-groups is fixed. The
initial priority in the group is as shown in table 8.2. However, the priority is changed whenever the
RFU performs processing. The priority in the group is like a loop, that is, the priority of the
processed ID number becomes the lowest, and the priority of the next ID number becomes the
highest.
Table 8.2
Correspondence between Activation Sources and ID Numbers
ID
Peripheral
Number
Module
0
USB
1
USB
2
USB
3
USB
4
USB
5
USB
6
USB
7
USB
8
SCI_0
9
SCI_0
10
SCI_2
11
SCI_2
12
MCIF
13
MCIF
Activation
Transfer
Source
Direction
RAM → USB
EP4
USB → RAM
EP5
RAM → USB
EP9
USB → RAM
EP10
RAM → USB
EP11
USB → RAM
EP12
RAM → USB
EP6I
USB → RAM
EP6O
SCI_0 → RAM
RDRF
RAM → SCI_0
TDRE
SCI_2 → RAM
RDRF
RAM → SCI_2
TDRE
MCIF →
RAM →
Multimedia card
Multimedia card
Multimedia
Multimedia
card → MCIF
card → RAM
Section 8 RAM-FIFO Unit (RFU)
Priority in
Transfer
Group (Initial
Value)
Size
Byte
Highest
Byte
Byte
Byte
Byte
Byte
Byte
Byte
Lowest
Byte
Highest
Byte
Byte
Byte
Byte
Byte
Lowest
Rev. 3.00 Jan 25, 2006 page 183 of 872
Priority
Inter-Groups
Group
(Fixed)
A
Highest
B
Lowest
REJ09B0286-0300
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