TMS320F28335, TMS320F28334, TMS320F28332
TMS320F28235, TMS320F28234, TMS320F28232
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SPRS439I–JUNE 2007–REVISED MARCH 2011
Table 6-35. SPI Slave Mode External Timing (Clock Phase = 1)(1) (2) (3) (4)
NO.
MIN
8tc(LCO)
MAX UNIT
12 tc(SPC)S
13 tw(SPCH)S
tw(SPCL)S
Cycle time, SPICLK
ns
Pulse duration, SPICLK high (clock polarity = 0)
Pulse duration, SPICLK low (clock polarity = 1)
Pulse duration, SPICLK low (clock polarity = 0)
Pulse duration, SPICLK high (clock polarity = 1)
Setup time, SPISOMI before SPICLK high (clock polarity = 0)
Setup time, SPISOMI before SPICLK low (clock polarity = 1)
0.5tc(SPC)S – 10
0.5tc(SPC)S – 10
0.5tc(SPC)S – 10
0.5tc(SPC)S – 10
0.125tc(SPC)S
0.5tc(SPC)S
ns
ns
ns
ns
0.5tc(SPC)S
0.5tc(SPC)S
0.5tc(SPC)S
14 tw(SPCL)S
tw(SPCH)S
17 tsu(SOMI-SPCH)S
tsu(SOMI-SPCL)S
18 tv(SPCL-SOMI)S
0.125tc(SPC)S
Valid time, SPISOMI data valid after SPICLK low
(clock polarity = 1)
0.75tc(SPC)S
tv(SPCH-SOMI)S
Valid time, SPISOMI data valid after SPICLK high
(clock polarity = 0)
0.75tc(SPC)S
21 tsu(SIMO-SPCH)S
tsu(SIMO-SPCL)S
Setup time, SPISIMO before SPICLK high (clock polarity = 0)
Setup time, SPISIMO before SPICLK low (clock polarity = 1)
35
35
ns
ns
22 tv(SPCH-SIMO)S
Valid time, SPISIMO data valid after SPICLK high
(clock polarity = 0)
0.5tc(SPC)S – 10
tv(SPCL-SIMO)S
Valid time, SPISIMO data valid after SPICLK low
(clock polarity = 1)
0.5tc(SPC)S – 10
(1) The MASTER / SLAVE bit (SPICTL.2) is cleared and the CLOCK PHASE bit (SPICTL.3) is cleared.
(2) tc(SPC) = SPI clock cycle time = LSPCLK/4 or LSPCLK/(SPIBRR + 1)
(3) Internal clock prescalers must be adjusted such that the SPI clock speed is limited to the following SPI clock rate:
Master mode transmit 25-MHz MAX, master mode receive 12.5-MHz MAX
Slave mode transmit 12.5-MHz MAX, slave mode receive 12.5-MHz MAX.
(4) The active edge of the SPICLK signal referenced is controlled by the CLOCK POLARITY bit (SPICCR.6).
12
SPICLK
(clock polarity = 0)
13
14
SPICLK
(clock polarity = 1)
17
18
SPISOMI
SPISIMO
SPISOMI Data Is Valid
21
Data Valid
22
SPISIMO Data
Must Be Valid
(A)
SPISTE
A. In the slave mode, the SPISTE signal should be asserted low at least 0.5 tc(SPC) before the valid SPI clock edge and
remain low for at least 0.5 tc(SPC) after the receiving edge (SPICLK) of the last data bit.
Figure 6-21. SPI Slave Mode External Timing (Clock Phase = 1)
Copyright © 2007–2011, Texas Instruments Incorporated
Electrical Specifications
149
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