Network Router User Manual

t
c(SPC)
+ SPI clock cycle time +
LSPCLK
4
or
LSPCLK
(SPIBRR ) 1)
+ t
c(LCO)
+ LSPCLK cycle time
Data Valid
22
SPISIMO
SPISOMI
SPICLK
(clock polarity = 1)
SPICLK
(clock polarity = 0)
SPISIMO Data
Must Be Valid
SPISOMI Data Is Valid
21
12
18
17
14
13
SPISTE
(see Note A)
(2)
SM320F2812-HT
www.ti.com SGUS062A–JUNE 2009–REVISED APRIL 2010
Table 6-24. SPI Slave Mode External Timing (Clock Phase = 1)
(1) (2) (3)
NO. MIN MAX UNIT
12 t
c(SPC)S
Cycle time, SPICLK 8tc(LCO) ns
t
w(SPCH)S
Pulse duration, SPICLK high (clock polarity = 0) 0.5t
c(SPC)S
– 10 0.5t
c(SPC)S
13
(4)
ns
t
w(SPCL)S
Pulse duration, SPICLK low (clock polarity = 1) 0.5t
c(SPC)S
– 10 0.5t
c(SPC)S
t
w(SPCL)S
Pulse duration, SPICLK low (clock polarity = 0) 0.5t
c(SPC)S
– 10 0.5t
c(SPC)S
14
(4)
ns
t
w(SPCH)S
Pulse duration, SPICLK high (clock polarity = 1) 0.5t
c(SPC)S
– 10 0.5t
c(SPC)S
Setup time, SPISOMI before SPICLK high (clock polarity =
t
su(SOMI-SPCH)S
0.125t
c(SPC)S
0)
17
(4)
ns
Setup time, SPISOMI before SPICLK low (clock polarity =
t
su(SOMI-SPCL)S
0.125t
c(SPC)S
1)
Valid time, SPIS OMI data valid after SPICLK high
t
v(SPCH-SOMI)S
0.75t
c(SPC)S
(clock polarity = 0)
18
(4)
ns
Valid time, SPISOMI data valid after SPICLK low
t
v(SPCL-SOMI)S
0.75t
c(SPC)S
(clock polarity = 1)
Setup time, SPISIMO before SPICLK high (clock polarity =
t
su(SIMO-SPCH)S
0
0)
21
(4)
ns
Setup time, SPISIMO before SPICLK low (clock polarity =
t
su(SIMO-SPCL)S
0
1)
Valid time, SPISIMO data valid after SPICLK high
tv
(SPCH-SIMO)S
0.5t
c(SPC)S
(clock polarity = 0)
22
(4)
ns
Valid time, SPISIMO data valid after SPICLK low
t
v(SPCL-SIMO)S
0.5t
c(SPC)S
(clock polarity = 1)
(1) The MASTER/SLAVE bit (SPICTL.2) is cleared and the CLOCK PHASE bit (SPICTL.3) is set.
(3) Not production tested.
(4) The active edge of the SPICLK signal referenced is controlled by the CLOCK POLARITY bit (SPICCR.6).
A. In the slave mode, the SPISTE signal should be asserted low at least 0.5tc(SPC) before the valid SPI clock edge and
remain low for at least 0.5tc(SPC) after the receiving edge (SPICLK) of the last data bit.
Figure 6-27. SPI Slave Mode External Timing (Clock Phase = 1)
Copyright © 2009–2010, Texas Instruments Incorporated Electrical Specifications 115
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