DS1921H データシートの表示（PDF） - Maxim Integrated

部品番号

コンポーネント説明

メーカー

DS1921H

High-Resolution Thermochron iButton Range H: +15°C to +46°C; Z: -5°C to +26°C

Maxim Integrated 

BIT DESCRIPTION

MIP: Mission in Progress

SIP: Sample in Progress

TLF: Temperature Low

Flag

THF: Temperature High

Flag

TAF: Timer Alarm Flag

BIT(S)

b5

b4

b2

b1

b0

DS1921H/Z

DEFINITION

If this bit reads 1 the DS1921H/Z has been set up for a mission and this

mission is still in progress. A mission is started if the EM bit of the

Control Register (address 20Eh) is 0 and a non-zero value is written to

the Sample Rate Register, address 20Dh. The MIP bit returns from logic

1 to logic 0 when a mission is ended. A mission will end with the first

write attempt (Copy Scratchpad command) to any register in the

address range of 200h to 213h. Alternatively, a mission can be ended by

directly writing to the Status Register and setting the MIP bit to 0. The

MIP bit cannot be set to 1 by writing to the status register.

If this bit reads 1 the DS1921H/Z is currently performing a temperature

conversion as part of a mission in progress. The mission samples occur

on the seconds rollover from 59 to 00. The SIP bit will change from 0 to

1 approximately 250ms before the actual temperature conversion begins

allowing the circuitry of the chip to wake-up. A temperature conversion

including a wake-up phase takes maximum 875ms. During this time

read accesses to the memory pages 17 and higher are permissible but

may reveal invalid data.

Logic 1 in the Temperature Low Flag bit indicates that a temperature

measurement during a mission revealed a temperature equal to or lower

than the value in the Temperature Low Threshold Register. The

Temperature Low Flag can be cleared at any time by writing this bit to 0.

This flag must be cleared before starting a new mission.

Logic 1 in the Temperature High Flag bit indicates that a temperature

measurement during a mission revealed a temperature equal to or

higher than the value in the Temperature High Threshold Register.

The Temperature High Flag can be cleared at any time by writing this bit

to 0. This flag must be cleared before starting a new mission.

If this bit reads 1, a RTC alarm has occurred (see section

TIMEKEEPING for details). The Timer Alarm Flag can be cleared at any

time by writing this bit to logic 0. Since the timer alarm cannot be

disabled, the TAF flag usually reads 1 during a mission. This flag should

be cleared before starting a new mission.

MISSION TIME STAMP

The Mission Time Stamp indicates the time and date of the first temperature conversion of a mission.

Subsequent temperature conversions will take place as many minutes apart from each other as specified

by the value in the Sample Rate Register. Mission samples occur on minute boundaries.

Mission Time Stamp Register Bitmap

ADDR b7

b6

b5

b4

b3

b2

b1

b0

0215h

0

10 Minutes

Single Minutes

0216h

0

12/24 20h. 10h.

AM/PM

Single Hours

0217h

0

0

10 Date

Single Date

0218h

0

0

0

10m.

Single Months

0219h

10 Years

Single Years

MISSION SAMPLES COUNTER

The Mission Samples Counter indicates how many temperature measurements have taken place during

the current mission in progress (if MIP = 1) or during the latest mission (if MIP = 0). The value is stored

as an unsigned 24-bit integer number. This counter is reset through the Clear Memory command.

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