CC2420

tsp

tch

tcl

tsd

thd

t

ns

 

 

 

 

 

 

SCLK

CSn

Write to register / RXFIFO:

SI SO

0

0

A5

A4

A3

A2

A1

A0

X DW15 DW14 DW13 DW12 DW11 DW10 DW9 DW8 X DW7 DW6 DW5 DW4 DW3 DW2 DW1 DW0

X

S7

S6

S5

S4

S3

S2

S1

S0

X

 

Write to TXFIFO:

SI

0

0

A5

A4

A3

A2

A1

A0

X DW7 DW6 DW5 DW4 DW3 DW2 DW1 DW0 X DW7 DW6 DW5 DW4 DW3 DW2 DW1 DW0

X

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SO

S7

S6

S5

S4

S3

S2

S1

S0

S7

S6

S5

S4

S3

S2

S1

S0

S7

S6

S5

S4

S3

S2

S1

S0

S7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Read from register / RXFIFO:

SI

SO

SI

SO

SI

SO

0

1

A5

A4

A3

A2

A1

A0

 

 

 

 

 

 

 

 

 

X

 

 

 

 

 

 

 

 

 

S7

S6

S5

S4

S3

S2

S1

S0

DR15

DR14 DR13 DR12 DR11 DR10 DR9 DR8

DR7

DR6

DR5

DR4

DR3

DR2

DR1

DR0

DR15

Read and write one byte to RAM: (multiple read / writes

also possible)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

A6

A5

A4

A3

A2

A1

A0

X B1

B0

0

X

X

X

X

X X DW7 DW6 DW5 DW4 DW3 DW2 DW1 DW0

X

S7

S6

S5

S4

S3

S2

S1

S0

 

 

 

 

X

 

 

 

 

DR7

DR6

DR5

DR4

DR3

DR2

DR1

DR0

 

DR7

Read one byte from RAM: (multiple reads also possible)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

A6

A5

A4

A3

A2

A1

A0

X

B1

B0

1

X

X

X

X

X

 

 

 

 

X

 

 

 

 

 

S7

S6

S5

S4

S3

S2

S1

S0

 

 

 

 

X

 

 

 

 

DR7

DR6

DR5

DR4

DR3

DR2

DR1

DR0

 

DR7

Figure 9. SPI timing diagram

Parameter

Symbol

Min

Max

Units

Conditions

 

 

 

 

 

 

SCLK, clock

FSCLK

 

10

MHz

 

frequency

 

 

 

 

 

 

 

 

 

 

 

SCLK low

tcl

25

 

ns

The minimum time SCLK must be low.

pulse

 

 

 

 

 

duration

 

 

 

 

 

 

 

 

 

 

 

SCLK high

tch

25

 

ns

The minimum time SCLK must be high.

pulse

 

 

 

 

 

duration

 

 

 

 

 

 

 

 

 

 

 

CSn setup

tsp

25

 

ns

The minimum time CSn must be low before the first

time

 

 

 

 

positive edge of SCLK.

 

 

 

 

 

 

CSn hold time

tns

25

 

ns

The minimum time CSn must be held low after the

 

 

 

 

 

last negative edge of SCLK.

SI setup time

tsd

25

 

ns

The minimum time data on SI must be ready

 

 

 

 

 

before the positive edge of SCLK.

 

 

 

 

 

 

SI hold time

thd

25

 

ns

The minimum time data must be held at SI, after

 

 

 

 

 

the positive edge of SCLK.

Rise time

trise

 

100

ns

The maximum rise time for SCLK and CSn

Fall time

tfall

 

100

ns

The maximum fall time for SCLK and CSn

Note: The set-up- and hold-times refer to 50% of VDD.

Table 4. SPI timing specification

13.3 Status byte

During transfer of the register access byte, command strobes, the first RAM address byte and data transfer to the TXFIFO, the CC2420 status byte is returned on the SO pin. The status byte contains 6 status bits which are described in Table 5.

Issuing a SNOP (no operation) command strobe may be used to read the status byte. It may also be read during access to chip functions such as register or FIFO access.

SWRS041B

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Texas Instruments 3138 155 232931 manual SPI timing specification Status byte, Parameter Symbol Min Max Units Conditions