MPC563XM Reference Manual, Rev. 1
888
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
23.4.9.1.4
SPRAM access direction
RW field defines the direction of the access in the SPRAM. The access direction is summarized in
.
23.4.9.1.5
Zero SPRAM Operation
Zero SPRAM operation is controlled by microcode field ZRO (1bit). When ZRO field is 0, the data portion
written in SPRAM or in P/DIOB (SPRAM read) registers will always be 0x0. When performing a Zero
SPRAM write operation, the RSIZ is relevant regardless of the P/D field (usually RSIZ is meaningful only
for P/D = 0), which means that zero SPRAM write operation can be performed with 32, 24 or 8 bits
according to SPRAM operation size. These conditions are summarized in
.
NOTE
When field STC is present, STC=11 also disables Zero SPRAM operation
(see
). The conflicts with DIOB operations (see
Section 23.4.9.1.6, “DIOB Stack Operation
resolved like a normal SPRAM operation (see
).
23.4.9.1.6
DIOB Stack Operation
SPRAM Indirect Addressing Mode (see
Section , “Indirect Addressing Mode
”) is used if STC field (2 bits)
exists in the microinstruction, controlling automatic increment/decrement of DIOB register, as shown in
, thus allowing stack operations. DIOB is incremented and decremented in word addresses,
only from bits 15 downto 2, i.e.: the bits 23 to 16 and 1 to 0 are left untouched by STC pre-decrement and
post-increment.
Table 23-55. SPRAM access direction
R/W
Meaning
0
read SPRAM parameter into P or DIOB registers
1
write SPRAM parameter from P or DIOB registers
Table 23-56. Zero SPRAM Operation
ZRO
RW
P/D
Meaning
0
0
0
Clear P register. Size is determined by RSIZ field. See
0
0
1
Clear DIOB (all 24 bits), independently of RSIZ
0
1
x
Clear SPRAM parameter. Size is determined by RSIZ field. See
1
RW
P/D
Regular SPRAM operation
Table 23-57. DIOB Post-Increment / Pre-Decrement - STC
STC
Meaning
00
Post-Increment of DIOB