CYRF6936 データシートの表示（PDF） - Cypress Semiconductor

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CYRF6936

WirelessUSB™ LP 2.4 GHz Radio SoC

Cypress Semiconductor 

CYRF6936

field is to infer an EOP condition from a configurable number of

successive noncorrelations; this option is not available in GFSK

mode and is only recommended when using SDR mode.

CRC16

The device may be configured to append a 16 bit CRC16 to each

packet. The CRC16 uses the USB CRC polynomial with the

added programmability of the seed. If enabled, the receiver

verifies the calculated CRC16 for the payload data against the

received value in the CRC16 field. The seed value for the CRC16

calculation is configurable, and the CRC16 transmitted may be

calculated using either the loaded seed value or a zero seed; the

received data CRC16 is checked against both the configured

and zero CRC16 seeds.

CRC16 detects the following errors:

■ Any one bit in error.

■ Any two bits in error (irrespective of how far apart, which

column, and so on).

■ Any odd number of bits in error (irrespective of the location).

■ An error burst as wide as the checksum itself.

Figure 2 shows an example packet with SOP, CRC16, and

lengths fields enabled, and Figure 3 shows a standard ACK

packet.

P ream ble

n x 16us

2nd Fram ing

S ym bol*

Figure 2. Example Packet Format

P

SOP 1

SOP 2

Length Payload D ata

CRC 16

1st Fram ing

S ym bol*

Packet

le n g th

1 Byte

P eriod

*Note:32 or 64us

Figure 3. Example ACK Packet Format

P re a m b le

n x 16us

2 n d F ra m in g

S y m b o l*

P

SOP 1

SOP 2

1 s t F ra m in g

S y m b o l*

CRC 16

C R C fie ld fro m

re c e iv e d p a c k e t.

2 B y te p e rio d s

*N o te :3 2 o r 6 4 u s

Packet Buffers

All data transmission and reception use the 16 byte packet

buffers - one for transmission and one for reception.

The transmit buffer allows loading a complete packet of up to 16

bytes of payload data in one burst SPI transaction. This is then

transmitted with no further MCU intervention. Similarly, the

receive buffer allows receiving an entire packet of payload data

up to 16 bytes with no firmware intervention required until the

packet reception is complete.

The CYRF6936 IC supports packets up to 255 bytes. However,

the actual maximum packet length depends on the accuracy of

the clock on each end of the link and the data mode. Interrupts

are provided to allow an MCU to use the transmit and receive

buffers as FIFOs. When transmitting a packet longer than 16

bytes, the MCU can load 16 bytes initially, and add further bytes

to the transmit buffer as transmission of data creates space in

the buffer. Similarly, when receiving packets longer than 16

bytes, the MCU must fetch received data from the FIFO

periodically during packet reception to prevent it from

overflowing.

Auto Transaction Sequencer (ATS)

The CYRF6936 IC provides automated support for transmission

and reception of acknowledged data packets.

When transmitting in transaction mode, the device automatically:

■ starts the crystal and synthesizer

■ enters transmit mode

■ transmits the packet in the transmit buffer

■ transitions to receive mode and waits for an ACK packet

■ transitions to the transaction end state when an ACK packet is

received or a timeout period expires

Similarly, when receiving in transaction mode, the device

automatically:

■ waits in receive mode for a valid packet to be received

■ transitions to transmit mode, transmits an ACK packet

■ transitions to the transaction end state (receive mode to await

the next packet, and so on.)

The contents of the packet buffers are not affected by the

transmission or reception of ACK packets.

Document #: 38-16015 Rev. *J

Page 5 of 28

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