MCP3912 datasheet(46/82 Pages) MICROCHIP

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MCP3912

DS20005348A-page 46

 2014 Microchip Technology Inc.

6.5.1

CONTINUOUS READ

The STATUSCOM register contains the read communica-

tion loop settings for the internal register address pointer

(READ<1:0> bits). For Continuous Read modes, the

address selection can take the following four values:

Any SDI data coming after the control byte is not

considered during a continuous read communication. The

following figures represent a typical continuous read

communication on all four ADC channels in TYPES mode

with the default settings (DR_LINK = 1, READ<1:0> = 10,

WIDTH_DATA<1:0> = 01) in case of the SPI Mode 0,0

(Figure 6-7) and SPI Mode 1,1 (Figure 6-8).

In SPI Mode (1,1), the SDO pin stays in the last state

(LSB of previous data) after a complete reading which

also allows seamless continuous Read mode (see

Figure 6-8).

FIGURE 6-7:

Typical Continuous Read Communication (WIDTH_DATA<1:0> = 01, SPI Mode 0,0).

FIGURE 6-8:

Typical Continuous Read Communication (WIDTH_DATA<1:0> = 01, SPI Mode 1,1).

TABLE 6-1:

ADDRESS SELECTION IN

CONTINUOUS READ

READ<1:0>

for Continuous Read

Communications

Static (no incrementation)

Groups

Types (default)

Full Register Map

Note:

For continuous reading of ADC data in

SPI Mode 0,0 (see Figure 6-7), once the

data has been completely read after a

data ready, the SDO pin will take the MSB

value of the previous data at the end of the

reading (falling edge of the last SCK

clock). If SCK stays idle at logic low (by

definition of Mode 0,0), the SDO pin will

be updated at the falling edge of the next

data ready pulse (synchronously with the

DR pin falling edge with an output timing

of tDODR) with the new MSB of the data

corresponding to the data ready pulse.

This mechanism allows the MCP3912 to

continuously read ADC data outputs

seamlessly, even in SPI Mode (0,0).

Don’t care

SCK

SDI

SDO

Hi-Z

0x01

24x

DATA_CH0

...

DATA_CH

Starts read sequence

at address00000

Complete READ sequence on ADC outputs channels 0 to

DATA_CH1

24x

...

24x

DATA_CH0

...

DATA_CH1

24x

...

24x

DATA_CH

Don’t care

DATA_CH0<23>

New data

DATA_CH0<23>

Old data

Complete READ sequence on new ADC outputs channels 0 to

Don’t care

SCK

SDI

SDO

Hi-Z

0x01

24x

DATA_CH0

...

DATA_CH

Starts read sequence

at address 00000

Complete READ sequence on ADC outputs channels 0 to

DATA_CH1

24x

...

24x

DATA_CH0

...

DATA_CH1

24x

...

24x

DATA_CH

Don’t care

Complete READ sequence on new ADC outputs, channels 0 to

Stays at

DATA_CH <0>

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