AS8501 - Data Sheet

austriamicrosystems

Revision 1.1, 04-April-06

www.austriamicrosystems.com

Page 15 of 40

Modes of operation, register OPM

Mode

Name

Description

mo3

mo2

mo1

mo0

0

MZL

Power on, loading from Zener-Zap

memory

0

0

0

0

1

MMS

Single measurement

0

0

0

1

2

MMD

Double measurement

(A,B,A,B …)

0

0

1

0

3

MWU

Wake-up

0

0

1

1

4

MAM

Alarm

0

1

0

0

5

MZP

Zener program/read

0

1

0

1

6

MPD

Power down

0

1

1

0

7

MSI

0

1

1

1

8-15

Reserved for testing

1)

1

x

x

x

Notes:

1)

Register addresses 12, 13, 14 and 15 are reserved for testing and future options; operations on these

registers must be avoided

7.5

Register description

In the following sections the register contents and their functions are described in detail. Since the length of some

registers is too long to present clearly, the registers are logically subdivided according to their functions and described

separately.

All internal functions are controlled by the contents of these registers which can be reloaded via the serial SDI interface at

any time. The AS8501 contains the following registers:

REGISTER

ADDRESS

SIZE

Contents

Detailled description see

OPM

0

4

Operating mode register

7.5.1

CRA

1

17

Measurement A configuration register

7.5.3

CRB

2

17

Measurement B configuration register

7.5.4

CRG

3

28

General configuration register

7.5.2

MSR

4

18

Measurement result register

7.5.9

ZZR

5

188

Zener-Zap register

7.5.5

CAR

6

110

Calibration register

7.5.6

TRR

7

20

Trimming register

7.5.7

THR

8

17

Alarm or wake-up threshold register

7.5.8

CFG

9

20

Test and special configuration register

1)

reserved

10-12

Test registers

This register is reserved for testing modes. Writing is possible only in mode 8. In order to assure

stable conditions in power-down modes MWU(3), MPD(6), TMSS(8) and MSI(13) the default

setting of the CFG register must be changed to x00003. It is not necessary to change this value

during normal operation.

Write commands not supported in a certain mode can be released immediately after the register address. The ASSP will

resume operation with the next start condition. Registers CAR and TRR are not buffered. Any read operation of the CAR

or TRR register may generate transients in the analog circuitry; further accurate measurements require a delay time for

settling.