MPC555
/
MPC556
QUEUED SERIAL MULTI-CHANNEL MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
14-23
A maximum of 32 commands can be in the queue. These bytes are assigned an ad-
dress from 0x00 to 0x1F. Queue execution by the QSPI proceeds from the address in
NEWQP through the address in ENDQP. (Both of these fields are in SPCR2.)
CR[0:F] —
Command RAM
0x30 51C0 – 0x30 51DF
Refer to
for more information on the command RAM.
14.7.3 QSPI Pins
Seven pins are associated with the QSPI. When not needed by the QSPI, they can be
configured for general-purpose I/O.
identifies the QSPI pins and their
functions. Register DDRQS determines whether the pins are designated as input or
output. The user must initialize DDRQS for the QSPI to function correctly.
7
6
5
4
3
2
1
0
CONT
BITSE
DT
DSCK
PCS3
PCS2
PCS1
PCS0
1
NOTES:
1. The PCS[0] bit represents the dual-function PCS[0]/
SS
.
—
—
—
—
—
—
—
—
CONT
BITSE
DT
DSCK
PCS3
PCS2
PCS1
PCS0
1
Command Control
Peripheral Chip Select
Table 14-19 Command RAM Bit Descriptions
Bit(s)
Name
Description
0
CONT
Continue
0 = Control of chip selects returned to PORTQS after transfer is complete.
1 = Peripheral chip selects remain asserted after transfer is complete.
1
BITSE
Bits per transfer enable
0 = Eight bits
1 = Number of bits set in BITS field of SPCR0.
2
DT
Delay after transfer
0 = Delay after transfer is 17
÷
F
SYS
.
1 = SPCR1 DTL[7:0] specifies delay after transfer PCS valid to SCK.
3
DSCK
PCS to SCK Delay
0 = PCS valid to SCK delay is one-half SCK.
1 = SPCR1 DSCKL[6:0] specifies delay from PCS valid to SCK.
4:7
PCS[3:0]
Peripheral chip selects. Use peripheral chip-select bits to select an external device for serial data
transfer. More than one peripheral chip select may be activated at a time, and more than one
peripheral chip can be connected to each PCS pin, provided proper fanout is observed. PCS[0]
shares a pin with the slave select (SS) signal, which initiates slave mode serial transfer. If SS is
taken low when the QSPI is in master mode, a mode fault occurs.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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