CYRF9935

Document Number: 001-88748 Rev. *G

Page 23 of 47

SPI Status in Command Phase

When a command is issued the radio always outputs the register 0x01 value. This helps the MCU to get the radio status without having

to ask for it specifically. The NOP command can be used to read radio status without performing operation.

SPI Command for Register Read and Write

There are two SPI commands that are used to access the radio register. R_REGISTER is used to read the content of a register.

W_REGISTER is used to write data to any register.

SPI Command for RX FIFO Access

There are two commands, R_RX_PAYLOAD and FLUSH_RX_FIFO to handle RX FIFO access. When CYRF9935 receives a data

packet, the data will be stored into RX FIFO. R_RX_PAYLOAD command is used to read the data from the RX FIFO. FLUSH_RX_FIFO

command clears bit 0 (RX_FIFO_NOT_EMPTY) of register 0x01 and bits 0–5 of register 0x1f. The RX_FIFO contents are not valid

after this command.

Table 26. SPI Command for NOP

Byte Num.

Phases

B7

B6

B5

B4

B3

B2

B1

B0

Note

Byte 1

Command

1

1

1

1

1

1

1

1

–

Table 27. SPI Command for Register Read

Byte Num.

Phases

B7

B6

B5

B4

B3

B2

B1

B0

Note

Byte 1

Command

0

0

Register Address

–

Byte 2

Data

Register Content

–

Table 28. SPI Command for Register Write

Byte Num.

Phases

B7

B6

B5

B4

B3

B2

B1

B0

Note

Byte 1

Command

0

1

Register Address

–

Byte 2

Data

Register Content

–

Table 29. SPI Command for R_RX_PAYLOAD

Byte Num.

Phases

B7

B6

B5

B4

B3

B2

B1

B0

Note

Byte 1

Command

1

0

0

0

0

0

0

0

Byte 2

Data

Packet RSSI

RX Pipe Number

Note 9, 10

Byte 3

Data

Reserved

Data Length

Note 11

Byte 4–35

Data

Read Data from RX FIFO

Table 30. SPI Command for FLUSH_RX_FIFO

Byte Num.

Phases

B7

B6

B5

B4

B3

B2

B1

B0

Note

Byte 1

Command

1

1

0

0

0

1

0

0

–

Notes

9. Packet RSSI

This field contains the RSSI value which was evaluated while receiving the packet.

10. RX Pipe Number

This field indicates to which pipe the data belongs.

11. Data Length

This field indicates how many bytes in RX FIFO should be read out. The maximum length is 32 Bytes. The minimum length is 1 Byte. The length from Byte Number

4-35 depends on this field.