AS5020

Rev. n/c

Page 4/11

Feb 2001

Measurement Modes

Two measurement modes can be selected by programming:

1) Single Read Out Mode (default)

2) Continuous Read Out Mode (OTP option)

Chip Select must be active low (PD/CS=0) to enable measurement and bring the output DATA

out of high impedance state.

After a minimum measurement period, the first falling edge of CLK latches the actual measured

angular value. The following rising edges shift the data bits out of the DATA pin, beginning with

the most significant bit. An NVR bit and even parity bit are added to the 6 bit angular value. The

NVR bit indicates a non-valid range given by bad magnet positioning.

PD/CS

CLK

DATA

D5

(MSB)

D5

(MSB)

D4

D0

NVR

Parity

Latch

actual value

Next

value

12

78

9

Reset not necessary in

Continuos Mode

Figure 1 SSI read out

In Single Read Out Mode the start of a new measurement has to be initiated with a short pulse

at PD/CS of at least 1 clockcycle. The following falling edge of CLK latches a new measured

value.

If the OTP option Continuous Read Out Mode is chosen, repeated angle measurement is

enabled by PD/CS=0. After each read out sequence the output shift register is automatically

refreshed. Fast transmission of the angular data can be performed without pulsing PD/CS.

Daisy Chain Configuration

In Singe Read Out mode, cascading allows Daisy Chain structures to minimise the

interconnection lines. Connecting DATA with PROG of the cascaded Sensor (see Fig. 2) allows

the read out of n sensors with the use of only three wires. The measurement data is shifted in

this configuration through the devices

After n x 9 clock cycles each value of n sensors is visible at pin DATA of the first sensor device.

A new measurement can be started with the falling edge of CLK after a power down pulse at

PD/CS.

AS5020

PROG

DATA

CLK

PD/CS

AS5020

PROG

DATA

CLK

PD/CS

AS5020

PROG

DATA

CLK

PD/CS

µµµµC

CLK

Power Down

Data In

n1

2

Figure 2 Typical Daisy Chain Configuration