DS9101 datasheet(34/55 Pages) MAXIM

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Clear Memory [with Password] [96h]

The Clear Memory with Password command is used to

prepare the device for another mission. This command

is only executed if no mission is in progress. After the

command code, the master must transmit the 64-bit

full-access password followed by an FFh dummy byte.

If passwords are enabled and the transmitted pass-

word is different from the stored full access password

or a mission is in progress, the Clear Memory com-

mand fails. The device stops communicating and waits

for a reset pulse. If the password was correct or if pass-

words were not enabled, the device clears the Mission

Timestamp register, Mission Samples Counter register,

and all alarm flags of the Alarm Status register. After

these cells are cleared, the MEMCLR bit of the General

Status register reads 1 to indicate the successful exe-

cution of the Clear Memory with Password command.

Clearing of the data-log memory is not necessary

because the Mission Samples Counter indicates how

many entries in the data-log memory are valid.

Forced Conversion [55h]

The Forced Conversion command can be used to mea-

sure the temperature and humidity without starting a

mission. After the command code, the master must

send one FFh byte to get the conversion started. The

conversion result is found as a 16-bit value in the Latest

Temperature Conversion Result and Latest Humidity

Conversion Result registers. This command is only exe-

cuted if no mission is in progress (MIP = 0). It cannot

be interrupted and takes maximum 666ms to complete.

During this time memory access through the 1-Wire

interface is blocked. The device behaves the same way

as during a mission when the sampling interferes with a

memory/control function command. See the

Memory

Access Conflicts section for details.

Start Mission [with Password] [CCh]

The DS1923 uses a control function command to start a

mission. A new mission can only be started if the previ-

ous mission has been ended and the memory has been

cleared. After the command code, the master must

transmit the 64-bit full access password followed by an

FFh dummy byte. If passwords are enabled and the

transmitted password is different from the stored full-

access password or a mission is in progress, the Start

Mission command fails. The device stops communicat-

ing and waits for a reset pulse. If the password was

correct or if passwords were not enabled, the device

starts a mission. If SUTA = 0, the sampling begins as

soon as the Mission Start Delay is over. If SUTA = 1, the

first sample is written to the data-log memory at the

time the temperature alarm occurred. However, the

Mission Samples Counter does not increment. One

sample period later, the Mission Timestamp register is

set and the regular sampling and logging begins. While

the device is waiting for a temperature alarm to occur,

the WFTA flag in the General Status register reads 1.

During a mission there is only read access to the regis-

ter pages.

Stop Mission [with Password] [33h]

The DS1923 uses a control function command to stop a

mission. Only a mission that is in progress can be

stopped. After the command code, the master must

transmit the 64-bit full access password followed by a

FFh dummy byte. If passwords are enabled and the

transmitted password is different from the stored full-

access password or a mission is not in progress, the

Stop Mission command fails. The device stops commu-

nicating and waits for a reset pulse. If the password

was correct or if passwords were not enabled, the

device clears the MIP bit in the General Status register

and restores write access to the register pages. The

WFTA bit is not cleared. See the description of the gen-

eral status register for a method to clear the WFTA bit.

Hygrochron Temperature/Humidity Logger

iButton with 8KB Data-Log Memory

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DS9101 Datasheet(PDF) 34 Page - Maxim Integrated Products

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