Freescale Semiconductor MCF5480 - Manual (Page 660)

MCF548x Reference Manual, Rev. 3
22-58 Freescale Semiconductor
Table 22-38. Header Bit Definitions
Bits Name Description
31–28 PEUSEL Primary execution unit select. Programs the channel to select a primary EU of a given type. A “No
primary EU selected” or a reserved value in this field will generate an unrecognized header error
condition during processing of the descriptor header.
0x0 No primary EU selected
0x1 AFEU
0x2 DEU
0x3 MDEU
0x4 RNG
0x5 Reserved
0x6 AESU
0x7–0xF Reserved
27–20 PMODE Primary execution unit mode. This data is passed directly to bits 7–0 of the mode register for the
specified EU. See
Section 22.14, “ EU Specific Data Packet Descriptors ” for descriptions of the
mode registers for each EU.
19–16 SEUSEL Secondary execution unit select. Programs the channel to select a secondary EU of a given type.
The MDEU is the only valid secondary EU. Any value other than ‘MDEU’ or ‘No secondary EU
selected” will generate an unrecognized header error condition during processing of the descriptor
header.
0x0 No secondary EU selected
0x1–0x02 Reserved
0x3 MDEU
0x4-0xF Reserved
Note: If the MDEU is used as a secondary EU, then the primary EU must be DEU, AESU, or AFEU.
All other combinations of primary EU and secondary MDEU processing will generate an
unrecognized header error condition.
15–8 SMODE Secondary execution unit mode. This data is passed directly to bits 7–0 of the mode register for the
specified EU. See
Section 22.14, “ EU Specific Data Packet Descriptors ” for descriptions of the
mode registers for each EU.
7–4 TYPE Descriptor type. Each type of descriptor determines the following attributes for the corresponding
data length/pointer pairs: the direction of the data flow; which EU is associated with the data; and
which internal EU address is used.
Table 22-39 lists the valid types of descriptors.
3–2 — Reserved. Set to zero