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RF65

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ADVANCED COMMUNICATIONS & SENSING

DATASHEET

The frame ends when NSS goes high. The next frame must start with an address byte. The SINGLE access mode is

actually a special case of FIFO / BURST mode with only 1 data byte transferred.

During the write access, the byte transferred from the slave to the master on the MISO line is the value of the written

5.2.2. FIFO

5.2.2.1. Overview and Shift Register (SR)

In packet mode of operation, data that has been received is stored in a configurable FIFO (First In First Out) device. It is

accessed via the SPI interface and provides several interrupts for transfer management.

The FIFO is 1 byte wide hence it only performs byte (parallel) operations, whereas the demodulator functions serially. A

shift register is therefore employed to interface the two devices. In Rx the shift register gets bit by bit data from the

demodulator and writes them byte by byte to the FIFO. This is illustrated in Figure 22.

byte1

byte0

FIFO

Rx Data

SR (8bits)

MSB

LSB

Figure 22. FIFO and Shift Register (SR)

Note

When switching to Sleep mode, the FIFO can only be used once the ModeReady flag is set (quasi immediate from

all modes)

5.2.2.2. Size

The FIFO size is fixed to 66 bytes.

5.2.2.3. Interrupt Sources and Flags



FifoNotEmpty: FifoNotEmpty interrupt source is low when byte 0, i.e. whole FIFO, is empty. Otherwise it is high. Note

that when retrieving data from the FIFO, FifoNotEmpty is updated on NSS falling edge, i.e. when FifoNotEmpty is

updated to low state the currently started read operation must be completed. In other words, FifoNotEmpty state

must be checked after each read operation for a decision on the next one (FifoNotEmpty = 1: more byte(s) to read;

FifoNotEmpty = 0: no more byte to read).



FifoFull: Fifofull interrupt source is high when the last FIFO byte, i.e. the whole FIFO, is full. Otherwise it is low.



FifoOverrunFlag: FifoOverrunFlag is set when a new byte is written by the SR while the FIFO is already full. Data is lost

and the flag should be cleared by writing a 1, note that the FIFO will also be cleared.



FifoLevel: Threshold can be programmed by FifoThreshold in RegFifoThresh. Its behavior is illustrated in figure below.

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