AN4440 datasheet(19/36 Pages) STMICROELECTRONICS

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AN4440

RFFE extended mode

4.1

Purpose

The extended mode allows updating simultaneously several registers (Ex: DAC A, B and C)

using a unique but longer frame than the standard one and is faster than using the trigger

mode.

4.2

Methodology

The frame is no longer the standard one as this methodology consists in defining the

quantity of consecutive registers to update, the first register address followed by each

Note:

Updated registers are consecutive. If a register which does not need an update is between

two registers that need a change, it is necessary to re-send its values.

4.3

Frame construction

The beginning of the frame has almost the same structure as other frames. Instead of the

write code, 3 x 0 bits indicates the use of the extended mode. Instead of the register

address, the byte count defines the quantity of registers that will be updated which

corresponds to the byte quantity after the start register.

Note:

Byte count starts from 0 so byte count = n means (n+1) registers updated.

Figure 21. Start of extended mode frame

This is followed by data values for each register:

Figure 22. First half of extended mode data

AN4440 Datasheet(PDF) 19 Page - STMicroelectronics