Datasheet

145
42023GS–SAM–03/2014
ATSAM4L8/L4/L2
Notes: 1. These values are based on simulation. These values are not covered by test limits in production.
2. Where:
Maximum SPI Frequency, Slave Input Mode
The maximum SPI slave input frequency is given by the following formula:
Where is the MOSI setup and hold time, USPI7 + USPI8 or USPI10 + USPI11 depending
on CPOL and NCPHA. is the maximum frequency of the CLK_SPI. Refer to the SPI
chapter for a description of this clock.
Maximum SPI Frequency, Slave Output Mode
The maximum SPI slave output frequency is given by the following formula:
Where is the MISO delay, USPI6 or USPI9 depending on CPOL and NCPHA. is
the SPI master setup time. refer to the SPI master datasheet for . is the maxi-
mum frequency of the CLK_SPI. Refer to the SPI chapter for a description of this clock.
is the maximum frequency of the SPI pins. refer to the I/O Pin Characteristics section for the
maximum frequency of the pins.
Table 9-61. USART3 in SPI mode Timing, Slave Mode
(1)
Symbol Parameter Conditions Min Max Units
USPI6 SPCK falling to MISO delay
V
VDDIO
from
3.0V to 3.6V,
maximum
external
capacitor =
40pF
593.9
ns
USPI7 MOSI setup time before SPCK rises
45.93 + t
SAMPLE
(2)
+
t
CLK_USART
USPI8 MOSI hold time after SPCK rises
47.03 -( t
SAMPLE
(2)
+
t
CLK_USART )
USPI9 SPCK rising to MISO delay 593.38
USPI10 MOSI setup time before SPCK falls
45.93 +( t
SAMPLE
(2)
+
t
CLK_USART )
USPI11 MOSI hold time after SPCK falls
47.03 -( t
SAMPLE
(2)
+
t
CLK_USART )
USPI12 NSS setup time before SPCK rises 237.5
USPI13 NSS hold time after SPCK falls -1.81
USPI14 NSS setup time before SPCK falls 237.5
USPI15 NSS hold time after SPCK rises -1.81
t
SAMPLE
t
SPCK
t
SPCK
2 t
CLKUSART
×
------------------------------------
1
2
---+
⎝⎠
⎛⎞
t
CLKUSART
×–=
f
SPCKMAX
MIN
f
CLKSPI
2×
9
-----------------------------
1
SPIn
------------(,)=
SPIn
f
CLKSPI
f
SPCKMAX
MIN
f
CLKSPI
2×
9
-----------------------------
f
PINMAX
,
1
SPIn t
SETUP
+
------------------------------------(,)=
SPIn
T
SETUP
T
SETUP
f
CLKSPI
f
PINMAX