Datasheet

SAM9263 [DATASHEET]
Atmel-6249N-ATARM-SAM9263-Datasheet_14-Mar-16
1046
Figure 46-8. EMAC RMII Mode
46.11 Peripheral Timings
46.11.1 SPI
46.11.1.1 Maximum SPI Frequency
The following formulas give maximum SPI frequency in Master read and write modes and in Slave read and write
modes.
Master Write Mode
The SPI is only sending data to a slave device such as an LCD, for example. The limit is given by SPI
2
(or SPI
5
)
timing. Since it gives a maximum frequency above the maximum pad speed (see Section 46.7 “I/Os”), the
maximum SPI frequency is the one from the pad.
Master Read Mode
t
valid
is the slave time response to output data after deleting an SPCK edge. For a non-volatile memory with t
valid
(or t
v
) = 12 ns, f
SPCK
max = 35.4 MHz at V
DDIO
= 3.3V.
Slave Read Mode
In slave mode, SPCK is the input clock for the SPI. The maximum SPCK frequency is given by setup and hold
timings SPI
7
/SPI
8
(or SPI
10
/SPI
11
). Since this gives a frequency well above the pad limit, the limit in slave read
mode is given by the SPCK pad.
Slave Write Mode
For 3.3V I/O domain and SPI6, f
SPCK
Max = 33 MHz. t
setup
is the setup time from the master before sampling data.
EREFCK
ETXEN
ETX[1:0]
ERX[1:0]
ERXER
ECRSDV
EMAC
21
EMAC
22
EMAC
23
EMAC
24
EMAC
25
EMAC
26
EMAC
27
EMAC
28
f
SPCK
Max
1
SPI
0
orSPI
3
()t
valid
+
------------------------------------------------------
=
f
SPCK
Max
1
SPI
6
orSPI
9
()t
setup
+
-------------------------------------------------------
=