In each case, the entire packet transaction takes place without
any need for MCU firmware action (as long as packets of 16
bytes or less are used). To transmit data, the MCU must load the
data packet to be transmitted, set the length, and set the TX GO
bit. Similarly, when receiving packets in transaction mode,
firmware must retrieve the fully received packet in response to
an interrupt request indicating reception of a packet.
Baseband and Framer
The baseband and framer blocks provide the DSSS encoding
and decoding, SOP generation and reception, CRC16
generation and checking, and EOP detection and length field.
Packet Buffers and Radio Configuration Registers
Packet data and configuration registers are accessed through
the SPI interface. All configuration registers are directly
addressed through the address field in the SPI packet (as in the
CYWUSB6934). Configuration registers allow configuration of
DSSS PN codes, data rate, operating mode, interrupt masks,
interrupt status, and so on.
The CYRF6936 IC supports the following data rates by
combining the PN code lengths and data transmission modes
described in the previous sections:
1000 kbps (GFSK)
250 kbps (32 chip 8DR)
125 kbps (64 chip 8DR)
62.5 kbps (32 chip DDR)
31.25 kbps (64 chip DDR)
15.625 kbps (64 chip SDR)
The CYRF6936 IC has an SPI interface supporting
communication between an application MCU and one or more
slave devices (including the CYRF6936). The SPI interface
supports single-byte and multi-byte serial transfers using either
4-pin or 3-pin interfacing. The SPI communications interface
consists of Slave Select (SS), Serial Clock (SCK), Master
Out-Slave In (MOSI), Master In-Slave Out (MISO), or Serial Data
SPI communication may be described as the following:
Functional Block Overview
2.4 GHz Radio
The radio transceiver is a dual conversion low IF architecture
optimized for power, range, and robustness. The radio employs
channel-matched filters to achieve high performance in the
presence of interference. An integrated Power Amplifier (PA)
provides up to +4 dBm transmit power, with an output power
control range of 34 dB in seven steps. The supply current of the
device is reduced as the RF output power is reduced.
Table 2. Internal PA Output Power Step Table
Typical Output Power (dBm)
Command Direction (bit 7) = ‘1’ enables SPI write transaction.
A ‘0’ enables SPI read transactions.
Command Increment (bit 6) = ‘1’ enables SPI auto address
increment. When set, the address field automatically
increments at the end of each data byte in a burst access.
Otherwise the same address is accessed.
Six bits of address
Eight bits of data
The device receives SCK from an application MCU on the SCK
pin. Data from the application MCU is shifted in on the MOSI pin.
Data to the application MCU is shifted out on the MISO pin. The
active LOW Slave Select (SS) pin must be asserted to initiate an
The application MCU can initiate SPI data transfers using a
multi-byte transaction. The first byte is the Command/Address
byte, and the following bytes are the data bytes shown in
The SPI communications interface has a burst mechanism,
where the first byte can be followed by as many data bytes as
required. A burst transaction is terminated by deasserting the
slave select (SS = 1).
The SPI communications interface single read and burst read
sequences are shown in
The SPI communications interface single write and burst write
sequences are shown in
This interface may be optionally operated in a 3-pin mode with
the MISO and MOSI functions combined in a single bidirectional
data pin (SDAT). When using 3-pin mode, user firmware must
ensure that the MOSI pin on the MCU is in a high impedance
state except when MOSI is actively transmitting data.
Before transmission or reception may begin, the frequency
synthesizer must settle. The settling time varies depending on
channel; 25 fast channels are provided with a maximum settling
time of 100
The ‘fast channels’ (less than 100
settling time) are every third
channel, starting at 0 up to and including 72 (for example, 0, 3,
6, 9 …. 69, 72).
Document #: 38-16015 Rev. *I
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