mc68331cpv20b1 Freescale Semiconductor, Inc, mc68331cpv20b1 Datasheet - Page 244

• Manufacturer Part Number: mc68331cpv20b1
• Description: Mc68331 32 Bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

D
D.4.16 CR[0:F] — Command RAM
*The PCS0 bit represents the dual-function PCS0/SS.
CONT — Continue
BITSE — Bits per Transfer Enable
DT — Delay after Transfer
DSCK — PCS to SCK Delay
PCS[3:0] — Peripheral Chip Select
D-36
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).
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.
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.
CONT
CONT
—
7
0 = Control of chip selects returned to PORTQS after transfer is complete.
1 = Peripheral chip selects remain asserted after transfer is complete.
0 = Eight bits
1 = Number of bits set in BITS field of SPCR0
0 = PCS valid to SCK transition is one-half SCK.
1 = SPCR1 DSCKL field specifies delay from PCS valid to SCK.
COMMAND CONTROL
BITSE
BITSE
—
6
Freescale Semiconductor, Inc.
For More Information On This Product,
DT
DT
—
5
Go to: www.freescale.com
REGISTER SUMMARY
DSCK
DSCK
—
4
PCS3
PCS3
—
3
PERIPHERAL CHIP SELECT
PCS2
PCS2
—
2
$YFFD40–$YFFD4F
PCS1
PCS1
—
1
USER’S MANUAL
PCS0*
PCS0*
MC68331
—
0