MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS

MA710 Rev. 1.0

www.MonolithicPower.com

13

9/27/2017

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SPI Communication

The sensor supports three types

of

SPI

operation:

 Read angle

 Read configuration register

 Write configuration register

Each operation has a specific frame structure

described below.

SPI Read Angle

Every 1µs, new data is transferred into the

output buffer. The master device triggers the

reading by pulling CS low.

When a trigger event is detected, the data

remains in the output buffer until the CS signal

is de-asserted (see Table 4).

Table 4: Sensor Data Timing

Event

Action

CS falling edge

Start reading and freeze

output buffer

CS rising edge

Release of the output buffer

See Figure 9 for a diagram of a full SPI angle

reading. See Figure 10 for a partial SPI angle

reading. A full angle reading requires 16 clock

pulses. The sensor MISO line returns:

MSB

LSB

MISO

Angle(15:0)

MOSI

0

The MagAlpha family has sensors with different

features and levels of resolution. See the data

output

length

section

in

the

General

Characteristics table on page 5 for the number

of useful bits delivered at the serial output. If the

data length is smaller than 16, the rest of the

bits sent are zeros. For example, a data output

length of 12 bits means that the serial output

delivers a 12-bit angle value with four bits of

zeros padded at the end (MISO state remains

zero). If the master sends 16 clock counts, the

MagApha replies with:

MSB

LSB

MISO

Angle(15:4)

0 0 0 0

MOSI

0

Angle reading can be therefore optimized,

without any loss of information, by reducing the

number of clock counts. In the case of a 12-bit

data output length, only 12 clock counts are

required to get the full sensor resolution.

MSB

LSB

MISO

Angle(15:4)

MOSI

0

If less resolution is needed, the angle can be

read by sending even fewer clock counts (since

the MSB is first).

In case of fast reading, the MagAlpha continues

sending the same data until the data is

refreshed. See the refresh rate section in the

General Characteristics table on page 5.

Figure 9: Diagram of a Full 16-Bit SPI Angle

Reading

Figure 10: Diagram of a Partial 8-Bit SPI Angle

Reading