Rainbow-electronics DS28EA00 Bedienungsanleitung PDF herunterladen (Seite 7)

DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO

7 of 29

Figure 4. 1-Wire CRC Generator

Polynomial = X

+ X

+ 1

STAGE

INPUT DATA

Memory Description

The memory of the DS28EA00 is shown in Figure 5. It consists of an 8-byte scratchpad and 3 bytes of backup

EEPROM. The first two bytes form the temperature readout register, which is updated after a temperature

conversion and is read-only. The next 3 bytes are user-writeable; they contain the Temperature High (TH) and the

Temperature Low (TL) alarm register and a configuration register. The remaining 3 bytes are “reserved”. They

power up with constant data and cannot be written by the user. The TH, TL, and configuration register data in the

scratchpad control the resolution of a temperature conversion and decide whether a temperature is considered as

“alarming”. TH, TL, and configuration can be copied to the EEPROM to become nonvolatile (NV). The scratchpad

is automatically loaded with EEPROM data when the DS28EA00 powers up.

Figure 5. Memory Map

BYTE

ADDRESS

SCRATCHPAD (POWER-UP STATE) BACKUP EEPROM

0 Temperature LSB (50h) N/A

1 Temperature MSB (05h) N/A

2 TH Register or User Byte 1* <--------> TH Register or User Byte 1

3 TL Register or User Byte 2* <--------> TL Register or User Byte 2

4 Configuration Register* <--------> Configuration Register

5 Reserved (FFh) N/A

6 Reserved (0Ch) N/A

7 Reserved (10h) N/A

*Power-up state depends on value(s) stored in EEPROM.

Temperature Readout Register

ADDR bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

0 2

-1

-2

-3

-4

LS Byte

1 S S S S S 2

MS Byte

1 2 3 4 5 6 7 8 9 10 11 12 ... 28 29

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Rainbow-electronics DS28EA00 Bedienungsanleitung Seite 7