MPC555
/
MPC556
QUEUED SERIAL MULTI-CHANNEL MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
14-16
To ensure proper operation, set the QSPI enable bit (SPE) in SPCR1 only after initial-
izing the other control registers. Setting this bit starts the QSPI.
Rewriting the same value to a control register does not affect QSPI operation with the
exception of writing NEWQP in SPCR2. Rewriting the same value to these bits causes
the RAM queue pointer to restart execution at the designated location.
Before changing control bits, the user should halt the QSPI. Writing a different value
into a control register other than SPCR2 while the QSPI is enabled may disrupt oper-
ation. SPCR2 is buffered, preventing any disruption of the current serial transfer. After
the current serial transfer is completed, the new SPCR2 value becomes effective.
14.7.1.1 QSPI Control Register 0
SPCR0 contains parameters for configuring the QSPI before it is enabled. The CPU
has read/write access to SPCR0, but the QSPI has read access only. SPCR0 must be
initialized before QSPI operation begins. Writing a new value to SPCR0 while the
QSPI is enabled disrupts operation.
Table 14-12 QSPI Register Map
Access
1
NOTES:
1. S = Supervisor access only
S/U = Supervisor access only or unrestricted user access (assignable data space).
Address
MSB
2
2. 8-bit registers, such as SPCR3 and SPSR, are on 8-bit boundaries. 16-bit registers such as SPCR0 are on 16-bit
boundaries.
LSB
S/U
0x30 5018
QSPI Control Register 0 (SPCR0)
for bit descriptions.
S/U
0x30 501A
QSPI Control Register 1 (SPCR1)
for bit descriptions.
S/U
0x30 501C
QSPI Control Register 2 (SPCR2)
for bit descriptions.
S/U
0x30 501E/
0x30 501F
QSPI Control Register 3 (SPCR3)
See
for bit descriptions.
QSPI Status Register (SPSR)
See
for bit descriptions.
S/U
0x30 5140 –
0x30 517F
Receive Data RAM (32 half-words)
S/U
0x30 5180 –
0x30 51BF
Transmit Data RAM (32 half-words)
S/U
0x30 51C0 –
0x30 51DF
Command RAM (32 bytes)
SPCR0
— QSPI Control Register 0
0x30 5018
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
MSTR
WOM
Q
BITS
CPOL CPHA
SPBR
RESET:
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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