Datasheet

DS1977
12 of 29
Figure 7-2. MEMORY/CONTROL FUNCTION FLOW CHART
99h
Copy
Scrpad.
[w/PW]
Master TX
E/S Byte
Authorization
Code Match?
DS1977 Copies Scratchpad
Data or Data from Password
Holding Register (if Password
Address) to Memory
Strong Pull-
up Valid?
Master
TX Reset?
AA = 1
Master TX
TA1 (T7:T0), TA2 (T15:T8)
Master TX
64-Bits [Password]
Password
Accepted?
DS1977 TX "0"
DS1977 TX "1"
Master
TX Reset?
N
Y
N
Y
N
Y
Y
N
Master
TX Reset?
Master RX "1"s
N
Y
N
Y
N
Y
Authorization
Code
Master Activates
Strong Pullup
N
Address of
Password?
Y
Read-
Access
Passw.?
Save to Read
Password Holding
Register
Y
N
Save to Full-
Access Password
Holding Register
More data
in SP?
Y
N
To Figure 7
3
rd
Part
From Figure 7
3rd Part
From Figure 7
1
st
Part
To Figure 7
1
st
Part
NOTE: The strong pullup
must be activated within
40µs after the last bit of the
password is transmitted.
Pullup duration: see t
SPUW