AN633
Rev. 0.7
17
Figure 9. Read the Response from Radio
If the CTS is polled over the SPI bus, first the host MCU should pull the NSEL pin low. This action should be
followed by sending out the 0x44 Read command ID and providing an additional eight clock pulses on the SCLK
pin. The radio will provide the CTS byte on its SDO pin during the additional clock pulses. If the CTS byte is 0x00,
then the response is not yet ready and the host MCU should pull up the NSEL pin and repeat the procedure from
the beginning as long as the CTS becomes 0xFF. If CTS is 0xFF, then the host MCU should keep the NSEL pin low
and provide clock cycles on the SCLK pin, as many as the data to be read out requires. The radio will clock out the
requested data on its SDO pin during the additional clock pulses.
Figure 10. Monitor CTS and Read the Response on the SPI Bus
Reading the response from the radio can be interrupted earlier. For example, if the host MCU asked for five bytes
of response, it may read fewer bytes in one SPI transaction. As long as a new command is sent, the radio keeps
the response for the last request in the command buffer. The host MCU can read the response several times in a
new SPI transaction. In such a case, the response is always provided from the first byte.
Notes:
Up to 16 bytes of response can be read from the radio in one SPI transaction. If more bytes are read, the
radio will provide the same 16 bytes of response in a circular manner.
If the command says that the host MCU expects N bytes of response, but during the read sequence, the
host MCU provides less than N bytes of clock pulses, it causes no issue for the radio. The response buffer
is reset if a new command is issued.
If the command says that the host MCU expects N bytes of response, but during the read sequence, the
host MCU provides more than N bytes of clock pulses, the radio will provide unpredictable bytes after the
first N bytes. The host MCU does not need to reset the SPI interface; it happens automatically if NSEL is
pulled low before the next command is sent.
0x44
NSEL
SDO
SD I
SCLK
CTS = 0xFF
Response Byte 0
Response Byte n
0x44
N SEL
SDO
SD I
SC LK
N SEL
SDO
SD I
SC LK
Re ad CT S
Re tr ievin g Re spo nse
CT S
Re sp onse Byte 0
Re sp onse Byte n
CT S V alue
N ot
0 xF F
0xF F
NSE L
SD O
SD I
SCLK
Summary of Contents for EZRADIOPRO Si4060
Page 24: ...AN633 24 Rev 0 7 Figure 20 Supply Current versus Time Diagram from Shutdown to RX State...
Page 67: ...AN633 Rev 0 7 67 Figure 48 Variable Length Packet Reception Flowchart...
Page 69: ...AN633 Rev 0 7 69 Figure 50 Packet Matching Reception Flowchart...
Page 73: ...AN633 Rev 0 7 73 Figure 54 Packet Reception with Automatic RX Hopping Flowchart...
Page 75: ...AN633 Rev 0 7 75 Figure 56 Packet Reception with Manual Rx Hopping...
Page 80: ...AN633 80 Rev 0 7 Figure 62 Long Packet Transmission Workflow...
Page 81: ...AN633 Rev 0 7 81 Figure 63 Long Packet RX Flowchart...
