CC2520_11 Datasheet, PDF (34/133 Pages) Texas Instruments – 2.4 GHZ IEEE 802.15.4/ZIGBEE RF TRANSCEIVER

CC2520 DATASHEET
2.4 GHZ IEEE 802.15.4/ZIGBEE® RF TRANSCEIVER
SWRS068 – DECEMBER 2007
10.4 SO
SO is serial data out from CC2520 to an external MCU. Data is clocked out on the negative edge of SCLK,
so the SO signal should be sampled on the following rising edge of SCLK. MSB (bit 7 in register definitions)
will be clocked out first.
SO is configured as an input when CSn is high or RESETn is low. Note that the SO pin should not be left
floating while in LPM1 or LPM2, as this will result in higher current consumption than necessary.
10.5 SPI Timing Requirements
SCLK
I
tsclk
tsclkh tsclkl
CSn
I
tcsckh tcsnh tcscks
tsis
SI
I1
0
tsih
7
6
5
4
SO
O
0
7
7
tsod
6
5
4
Figure 6: SPI timing relationships
The following table and figure shows required timing relations between an external microcontroller and the
SPI interface on CC2520.
PARAMETER
tcscks
tcsckh
tcsnh
tsclk
tsclkh
tsclkl
tsis
tsih
tsod
Table 7: SPI timing requirements
DESCRIPTION
CSn to SCLK setup time
SCLK to CSn hold time
CSn high
SCLK period
SCLK high time
SCLK low time
SI to SCLK setup time
SI to SCLK hold time
SCLK to SO delay
MIN
TYP
62.5
62.5
62.5
125
62.5
62.5
31
31
MAX
31
UNIT
ns
ns
ns
ns
ns
ns
ns
ns
ns
34
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