ADFS5758 datasheet(47/75 Pages) AD

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Data Sheet

ADFS5758

Rev. 0 | Page 47 of 75

Key Sequencing (Command 010)

Writing Command 010 enables key sequencing mode. Sequencing

starts with a write to the key register with Key Code 0x1ADC,

starting on Channel 0 and continuing to Channel N − 1, where N

is the depth, with each 0x1ADC command. This mode enables

user control of the switching of channels during sequencing

because the switch occurs only for each specific key code

command, rather than for each valid SPI frame, as in the case of

automatic sequencing mode. When the sequence is completed, it

starts again with Channel 0 until disabled. Command 000 and

Command 001 must be used to configure all the required

channels before Command 0b010 is issued to enable key

sequencing mode (see Figure 87). If the sequencing is disabled

and later reenabled, the sequencer is reset to recommence

converting on the first channel in the sequence.

Automatic Sequencing (Command 011)

Sequencing starts on the next valid SPI frame, starting with

Channel 0 and continuing to Channel N − 1, where N is the

depth, on each valid SPI frame. When the sequence is complete, it

starts again with Channel 0 until disabled. As with the key

sequencing mode, Command 000 and Command 001 must be

used to configure all the required channels before Command 011

is issued to enable automatic sequencing mode (see Figure 87).

If the sequencing is disabled and later reenabled, the sequencer

is reset to recommence converting on the first channel in the

sequence. When reenabled, the channels do not need to be

reconfigured, unless the desired list of nodes changes.

Single Immediate Conversion (Command 100)

This mode initiates a single conversion on the node currently

selected in the ADC input select bits of the ADC_CONFIG

sequence, meaning that it must be reenabled if required. The

sequencer does not need to be reconfigured because the

configuration of sequencer depth and channels is stored.

Single Key Conversion (Command 101)

This mode is used to set up an individual ADC input node to be

converted at some future time, initiated by writing the 0x1ADC

key code to the key register. This mode is useful if the user

configuration space is locked and an ADC conversion is

required without unlocking the user configuration space.

Sequencing Mode Setup

A list of the relevant ADC sequencer commands is shown in

Table 21

. These commands are available in the ADC_CONFIG

default depth (000) is equivalent to one diagnostic channel up

to a binary depth value of 111, which is equivalent to eight

channels.

Three steps are involved in setting up the sequencer:

1. Select the depth.

2. Load the channels into the sequencer N times for N channels.

3. Enable the sequencer.

An example of configuring the sequencer to monitor three

ADC nodes is shown in Figure 87.

Table 21. Command Bits

Value

Description

000

Set the sequencer depth (0 to 7)

001

Load sequencer Channel N with the selected ADC input

010

Enable or disable the key sequencer

011

Enable or disable the automatic sequencer

100

Perform a single conversion on the currently selected

ADC input (D4 to D0)

101

Set up single key conversion, that is, select the ADC

mux input to be used when triggered with a write to

the key register (this is outside of the key sequencing

mode)

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