QUEUED SERIAL MODULE
M68HC16 Z SERIES
9-18
USER’S MANUAL
Delay after transfer can be used to provide a peripheral deselect interval. A delay can
also be inserted between consecutive transfers to allow serial A/D converters to com-
plete conversion. Writing a value to DTL[7:0] in SPCR1 specifies a delay period. The
DT bit in each command RAM byte determines whether the standard delay period (DT
= 0) or the user-specified delay period (DT = 1) is used. The following expression is
used to calculate the delay:
where DTL equals {1, 2, 3,..., 255}.
A zero value for DTL[7:0] causes a delay-after-transfer value of 8192/f
sys
.
Adequate delay between transfers must be specified for long data streams because
the QSPI requires time to load a transmit RAM entry for transfer. Receiving devices
need at least the standard delay between successive transfers. If the system clock is
operating at a slower rate, the delay between transfers must be increased proportion-
ately.
Table 9-3 Bits Per Transfer
BITS[3:0]
Bits Per Transfer
0000
16
0001
Reserved
0010
Reserved
0011
Reserved
0100
Reserved
0101
Reserved
0110
Reserved
0111
Reserved
1000
8
1001
9
1010
10
1011
11
1100
12
1101
13
1110
14
1111
15
Delay after Transfer
32
DTL[7:0]
×
f
sys
------------------------------------
=
if DT = 1
Standard Delay after Transfer
17
f
sys
---------
=
if DT = 0
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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