Rainbow Electronics DS1822 - Manual (Page 12)

DS1822
12 of 20
ROM COMMANDS FLOW CHART Figure 11
CCh
SKIP ROM
COMMAND
MASTER T
X
RESET PULSE
DS1822 T X
PRESENCE
PULSE
MASTER T
X
ROM
COMMAND
33h
READ ROM
COMMAND
55h
MATCH ROM
COMMAND
F0h
SEARCH ROM
COMMAND
ECh
ALARM SEARCH
COMMAND
MASTER T
X
BIT 0
DS1822 T
X
BIT 0
DS1822 T
X
BIT 0
MASTER T X BIT 0
BIT 0
MATCH?
MASTER T
X
BIT 1
BIT 1
MATCH?
BIT 63
MATCH?
MASTER T
X
BIT 63
N
Y Y Y Y Y
N N N N
N
N
N
Y
Y
Y
DS1822 T
X
BIT 1
DS1822 T
X
BIT 1
MASTER T
X
BIT 1
DS1822 T
X
BIT 63
DS1822 T
X
BIT 63
MASTER T
X
BIT 63
BIT 0
MATCH?
BIT 1
MATCH?
BIT 63
MATCH?
N
N
N
Y
Y
Y
DS1822 T
X
FAMILY CODE
1 BYTE
DS1822 T
X
SERIAL NUMBER
6 BYTES
DS1822 T X
CRC BYTE
DS1822 T
X
BIT 0
DS1822 T
X
BIT 0
MASTER T X BIT 0
N
Y
DEVICE(S)
WITH ALARM
FLAG SET?
Initialization
Sequence
MASTER T
X
FUNCTION
COMMAND
(FIGURE 12)