MAQ430 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & UVW OUTPUTS

MAQ430 Rev. 1.2

www.MonolithicPower.com

15

8/8/2022

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SPI Write Register

Table

5

shows

the

programmable

8-bit

registers. Data written to these registers are

stored in the on-chip non-volatile memory and

reloaded automatically during power on. The

factory default register values are shown in

Table 6.

A write register operation is constituted of two

16-bit frames. The first frame sends a write

request which contains the 3-bit write command

(100) followed by the 5-bit register address and

the 8-bit value (MSB first). The second frame

returns

the

newly

written

register

value

(acknowledge).

The on-chip memory is guaranteed to endure

1,000 write cycles at 25°C.

It is important to wait 20ms between the first

and the second frame. This is the time taken to

write

the

non-volatile

memory.

Failure

to

implement this wait period results in the

register

’s previous value being read. Note that

this delay is only required after a write request.

A read register request and read angle do not

require this wait time.

The first 16-bit SPI frame (write request) is:

MSB

LSB

MISO

Angle(15:0)

command

reg. address

reg. value

MOSI

1

0

0

A4 A3 A2 A1 A0 V7 V6 V5 V4 V3 V2 V1 V0

The second 16-bit SPI frame (response) is:

reg. value

MISO V7 V6 V5 V4 V3 V2 V1 V0

0 0 0 0 0 0 0 0

MSB

LSB

MOSI

0

The read-back register content can be used to

verify the register programming. See Figure 13

for a complete transmission overview.

For example, to set the value of the output

rotation direction (RD) to counterclockwise

(high), write register 9 by sending the following

first frame:

MSB

LSB

MISO

Angle(15:0)

command

reg. address

reg. value

MOSI

1

0

0

0

1

0

0

1

1 0 0 0 0 0 0 0

Send the second frame after a 20ms wait time.

If the register is correctly written, the reply is:

reg. value

MISO 1 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

MSB

LSB

MOSI

0

See Figure 14 for a complete example.

Figure 13: Overview of Two 16-Bit Frames Write Register Operation