DS1921 DALLAS [Dallas Semiconductor], DS1921 Datasheet - Page 27

• Manufacturer Part Number: DS1921
• Description: High-Resolution Thermochron iButton
• Manufacturer: DALLAS [Dallas Semiconductor]

ROM FUNCTIONS FLOW CHART Figure 13-1
1)
2)
Serial Number
Temp. Range
To be transmitted or received at Overdrive speed if
OD = 1.
The Presence Pulse will be short if OD = 1.
Family Code
DS1921 TX
DS1921 TX
DS1921 TX
CRC Byte
Code and
6 Bytes
ROM?
1 Byte
Read
33H
From Memory Functions
Flow Chart (Figure 10)
Y
1)
1)
1)
N
Master TX Bit 0
Master TX Bit 1
Master TX Bit 63
Bit 63 Match?
Bit 0 Match?
Bit 1 Match?
ROM?
Match
55H
Y
Y
Y
Y
Function Command
N
N
N
1)
1)
1)
Master TX ROM
Presence Pulse
Reset Pulse?
N
Reset Pulse
DS1921 TX
Master TX
Short
N
N
N
27 of 44
DS1921 TX Bit 0
DS1921 TX Bit 0
Master TX Bit 0
DS1921 TX Bit 1
DS1921 TX Bit 1
Master TX Bit 1
DS1921 TX Bit 63
DS1921 TX Bit 63
Master TX Bit 63
Bit 63 Match?
Bit 0 Match?
Bit 1 Match?
Y
Search
ROM?
F0H
Flow Chart (Figure 10)
To Memory Functions
N
2)
1)
Y
Y
Y
Y
OD = 0
1)
1)
1)
1)
1)
1)
1)
1)
1)
N
N
N
N
N
DS1921 TX Bit 0
DS1921 TX Bit 0
Master TX Bit 0
DS1921 TX Bit 1
DS1921 TX Bit 1
Master TX Bit 1
DS1921 TX Bit 63
DS1921 TX Bit 63
Master TX Bit 63
Cond. Search
Bit 63 Match?
Bit 0 Match?
Bit 1 Match?
Cond. Met?
ROM?
ECH
Y
Y
Y
Y
Y
1)
1)
1)
1)
1)
1)
1)
1)
1)
N
From Figure 13
From Figure 13
To Figure 13
To Figure 13
2
2
2
2
nd
nd
nd
nd
Part
Part
Part
Part
DS1921H/Z