DS1925

iButton High-Capacity Temperature Logger

with 122KB Data-Log Memory

www.maximintegrated.com

Maxim Integrated │ 41

1-Wire Communication Examples

Write Scratchpad, reaching the end of the Scratchpad (cannot fail)

RST

PD

Select

WS

TA

<data to EOS>

CRC16

FF loop

Read Scratchpad (cannot fail)

RST

PD

Select

RS

TA-E/S

<data to EOS>

CRC16

FF loop

XPC Copy Scratchpad

RST

PD

Select

XPC

0Ch

CPS

TA-E/S

<PW/dummy>

CRC16

Release byte

(SPU)

FFh

Result Loop

XPC Clear Memory (log)

RST

PD

Select

XPC

0Ah

CM

01

PW

CRC16

<Release byte>

(SPU)

FFh

Result Loop

To verify success, read the General Status register at address 0215h. If MEMCLR is 1, the command was executed successfully.

XPC Forced Conversion

RST

PD

Select

XPC

01h

FC

CRC16

<Release byte>

(SPU)

FFh

Temp Result

CRC16

To read the result and to verify success, read the addresses 020Ch−020Fh (results) and the Device Samples Counter at address 0223h−0225h.

If the count has incremented, the command was executed successfully.

XPC Read Battery Voltage

RST

PD

Select

XPC

01h

RB

CRC16

<Release byte>

(SPU)

FFh

Battery Result

CRC16

XPC Start Mission

RST

PD

Select

XPC

09h

SM

<PW/dummy>

CRC16

Release byte

(SPU)

FFh

Result Loop

To verify success, read the General Status register at address 0215h. If MIP is 1 and MEMCLR is 0, the command was executed successfully.

XPC Stop Mission

RST

PD

Select

XPC

09h

STP

<PW/dummy>

CRC16

Release byte

(SPU)

FFh

Result Loop

To verify success, read the General Status register at address 0215h. If MIP is 0, the command was executed successfully.

XPC Read Memory (Success)

RST

PD

Select

XPC

0Bh

RR

TA1 TA2

PW

CRC16

<Release byte>

(SPU)

FFh

<Data bytes>

CRC16

<Release byte>

(SPU)

FF loop

LOOP UNTIL END OF MEMORY