Texas Instruments TRF7970A Manual page 40

TRF7970A
SLOS743L – AUGUST 2011 – REVISED MARCH 2017
MOSI Transitions on Data Clock
t
STE,LEAD
MOSI Valid on Data Clock Falling Edge
Slave Select
1/f
UCxCLK
DATA_CLK
t t
LO/HI LO/HI
MOSI b7
MISO
The read command is sent out on the MOSI pin, MSB first, in the first eight clock cycles. MOSI data
changes on the rising edge, and is validated in the reader on the falling edge, as shown in
During the write cycle, the serial data out (MISO) is not valid. After the last read command bit (B0) is
validated at the eighth falling edge of SCLK, valid data can be read on the MISO pin at the falling edge of
SCLK. It takes eight clock edges to read out the full byte (MSB first). See
specifications related to
Figure 6-20 and Figure 6-21
DATA_CLK
MOSI
B7 B6 B5 B4
MISO
Slave
Select
Figure 6-20. Continuous Read Operation Using SPI With Slave Select
40 Detailed Description
Write
Rising Edge
t t
SU,SI HD,SI
b6...b1 b0
Don't Care
Figure 6-19. SPI With Slave Select Timing Diagram
Figure 6-19.
show the continuous read operation.
Write
Address Byte
No Data Transitions (All High or Low)
B3 B2 B1 B0
Don't Care B7 B6 B5 B4
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Data Transition is on Data Clock
MISO Valid on Data Clock Falling Edge
t
t
SU,SO
HD,SO
b7
Read Data
Byte 1
B3 B2 B1 B0
Copyright © 2011–2017, Texas Instruments Incorporated
TRF7970A
Read
t
STE,LAG
Rising Edge
No Data Transitions
(All High or Low)
t
VALID,SO
b6...b1 b0
Figure
Section 5.4 for electrical
Read Data
Byte n
No Data Transitions (All High or Low)
B7 B6 B5 B4 B3 B2 B1 B0
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t
STE,DIS
6-19.