AS3955 datasheet(62/111 Pages) AMSCO

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[v1-01] 2015-Apr-29

AS3955 − Detailed Description

Reading Received Data from Buffer

Reading received data from the buffer is similar to reading data

from an addressable registers. Difference is that, in case of

reading more bytes, they all come from the buffer. The

command mode code 101b indicates buffer operations. In case

the command is terminated by putting /SS high before a packet

of 8 bits composing one byte is read that particular byte is

considered read.

Direct Command Mode

Direct Command Mode is comprised of one command byte

followed by argument byte. SPI operation mode bits 11b

indicate Direct Command Mode. The following six bits define

command code, sent MSB first. Last two bits in argument byte

indicate success of the direct command. Value 01h of the

argument byte indicates that command was accepted, while

value 02h indicates rejected due to internal access priorities.

The argument byte does not provide information on timing of

the command execution.

Figure 65:

Sending a Direct Command over SPI

SCLK rising

edge Data is

transferred

from µC

SCLK falling

edge Data is

sampled

Two leading

ONE indicate

COMMAND

Mode

/SS

SCLK

MOSI

AS3955 Datasheet(PDF) 62 Page - ams AG