MA780 – 8-BIT TO 12-BIT LOW-POWER ANGLE SENSOR

MA780 Rev. 1.2

MonolithicPower.com

12

8/30/2021

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SPI Communication

Users can accomplish the following using the

SPI:

 Read angle

 Read register

 Write register

 Store a single register to NVM

 Store all registers to NVM

 Restore all registers from NVM

 Clear error flags

SPI Read Angle

Every 1µs, new data is transferred into the output

buffer. The master device initiates this process

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 5).

Table 5: Sensor Data Timing

Event

Action

/CS falling edge

Start reading and freeze the

output buffer

/CS rising edge

Release the output buffer

Figure 14 shows a diagram of a full SPI angle

reading.

Figure 14: Diagram of a Full 16-Bit SPI Angle

Reading

Figure 15 shows a partial SPI angle reading.

Figure 15: Diagram of a Partial 8-Bit SPI Angle

Reading

A full angle reading requires 16 clock pulses.

The sensor

’s MISO line then returns the

following:

MSB

LSB

MISO

Angle(15:0)

MOSI

0

If less resolution is sufficient, the angle can be

read by sending fewer clock counts (since the

MSB is first). If the reading cycle is shorter than

the refresh time, the MA780 continues sending

the same data until the data refreshes (for the

refresh rate, see the Electrical Characteristics

section on page 4).

SPI Read Register

A read register operation consists of two 16-bit

frames. The first frame sends a read request,

which contains the 3-bit read command (010)

followed by the 5-bit register address. The last 8

bits of the frame must all be set to 0. The second

frame returns the 8-bit register value (MSB byte)

with an 8-bit angle value.

First 16-bit SPI frame (read request):

MSB

LSB

MISO

Angle(15:0)

Command

Reg. Address

MOSI

0

1

0

A4 A3 A2 A1 A0

0 0 0 0 0 0 0 0

Second 16-bit SPI frame (response):

Reg. Value

MISO

Angle(15:8)

V7 V6 V5 V4 V3 V2 V1 V0

MSB

LSB

MOSI

0

For example, to check the value of the ERRPAR

parameter

(parity

error

on

register

write

command), read register 26 (bit[3]) by sending

the following first frame:

MSB

LSB

MISO

Angle(15:0)

Command

Reg. Address

MOSI

0

1

0

1

1

0

1

0

0 0 0 0 0 0 0 0

In the second frame, the MA780 replies:

Reg. Value

MISO

Angle(15:8)

X X X X ERRPAR X X X

MSB

LSB

MOSI

0

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Angle

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

0x0000

/CS

SCLK

MISO

MOSI

15

14

13

12

11

10

9

8

15

14

13

12

11

10

9

8

Angle

15

14

13

12

11

10

9

8

0x00

/CS

SCLK

MISO

MOSI