MB97R8110 datasheet(13/63 Pages) RAMXEED

13 / 63 page

DS411-00007-3v1-E

MB97R8110

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3.7 Power sequence and Arbitration

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3.7.1 Arbitration between RF and SPI slave communication

The arbitration feature manages memory access from either RF interface or SPI interface in order to avoid any

interruption to each other. SPIREQ and SPIACK manages to switch communication from RF interface to SPI

interface by activating VDD, and vice versa.

In order to start SPI slave communication, the external SPI master device connected to this LSI shall set SPIREQ

to “H” level to request communication. Upon the request, this LSI sets SPIACK to “H” level after completing

active communication from RF interface. Then XCS shall be set to “L” level, and SPI slave communication will

be ready. It is possible to start SPI slave communication during the period when SPIACK is “L” level, even if

XCS is “L” level.

The example of arbitration sequence between RF and SPI slave communication is shown in Figure 3.7.1.

As described, when SPIACK is “L” level, any command input from SPI slave interface is prohibited even if

XCS is in “L” level. When SPIACK is “H” level, any command from RF interface is invalid and SPI slave

communication will be continued. In this case, SPIREQ shall be set to “L” after completing active

communication from SPI interface in order to switch to RF communication.

Figure 3.7.1 －The arbitration sequence between RF communication and SPI slave communication

In addition, SPI master function and Key Matrix scan function works as RF communication under the arbitration

sequence above.

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