Datasheet

DS1977
11 of 29
Figure 7-1. MEMORY/CONTROL FUNCTION FLOW CHART
N
Master TX Memory
Function Command
0Fh
Write
Scratchpad
Master TX
TA1 (T7:T0), TA2 (T15:T8)
DS1977 sets Scratch-
pad Offset = (T5:T0)
and Clears (PF, AA)
Master TX Data Byte
to Scratchpad Offset
DS1977 sets (E5:E0)
= Scratchpad Offset
Master
TX Reset?
Scratch-
pad Offset =
3Fh?
Master RX CRC16 of
Command, Address Data
DS1977 Incre-
ments Scratch-
pad Offset
Master RX "1"s
Master
TX Reset?
Master
TX Reset?
Partial
Byte Written?
PF = 1
AAh
Read
Scratchpad
Master RX
TA1 (T7:T0)
Master RX
TA2 (T15:T8)
Master RX Ending
Offset with Data
Status (E/S)
Master
TX Reset?
Scratch-
pad Offset =
3Fh?
Master RX CRC16 of
Command, Address Data,
E/S Byte, and Data Starting
at the Target Address
DS1977 Incre-
ments Scratch-
pad Offset
Master RX "1"s
Master
TX Reset?
DS1977 sets Scratch-
pad Offset = (T5:T0)
Master RX Data Byte
from Scratchpad Offset
From ROM Functions
Flow Chart (Figure 9)
To ROM Functions
Flow Chart (Figure 9)
N
Y
N
Y
N
Y
N
Y
N
Y
N
Y
N
Y
N
Y
N
Y
N
Y
Address of
Password?
DS1977 sets Scratchpad
Offset = (T5:T3,0,0,0) and
Clears (PF, AA, T2:T0)
Y
Master TX one or both
8-byte passwords
To Figure 7
2
nd
Part
From Figure 7
2
nd
Part