D.4.16 CR[0:F] — Command RAM
$YFFD40–$YFFD4F
7
6
5
4
3
2
1
0
CONT
BITSE
DT
DSCK
PCS3
PCS2
PCS1
PCS0*
—
—
—
—
—
—
—
—
CONT
BITSE
DT
DSCK
PCS3
PCS2
PCS1
PCS0*
COMMAND CONTROL
*The PCS0 bit represents the dual-function PCS0/SS.
PERIPHERAL CHIP SELECT
Command RAM is used by the QSPI when in master mode. The CPU32 writes one
byte of control information to this segment for each QSPI command to be executed.
The QSPI cannot modify information in command RAM.
Command RAM consists of 16 bytes. Each byte is divided into two fields. The periph-
eral chip-select field enables peripherals for transfer. The command control field pro-
vides transfer options.
A maximum of 16 commands can be in the queue. Queue execution proceeds from
the address in NEWQP through the address in ENDQP (both of these fields are in
SPCR2).
D
CONT — Continue
0 = Control of chip selects returned to PORTQS after transfer is complete.
1 = Peripheral chip selects remain asserted after transfer is complete.
BITSE — Bits per Transfer Enable
0 = Eight bits
1 = Number of bits set in BITS field of SPCR0
DT — Delay after Transfer
The QSPI provides a variable delay at the end of serial transfer to facilitate interfacing
with peripherals that have a latency requirement. The delay between transfers is de-
termined by the SPCR1 DTL field.
DSCK — PCS to SCK Delay
0 = PCS valid to SCK transition is one-half SCK.
1 = SPCR1 DSCKL field specifies delay from PCS valid to SCK.
PCS[3:0] — Peripheral Chip Select
Peripheral chip-select bits are used 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 ob-
served. PCS0 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 oc-
curs.
MOTOROLA
D-36
REGISTER SUMMARY
MC68331
USER’S MANUAL
MOTOROLA [ MOTOROLA ]
