1024-Bit, 1-Wire EEPROM
for Automotive Applications
DS243-A1
BUS MASTER Tx MEMORY
FUNCTION COMMAND
FROM ROM FUNCTIONS
FLOW CHART (FIGURE 9)
TO FIGURE 7
2ND PART
0Fh
AAh
N
N
WRITE SCRATCHPAD?
READ SCRATCHPAD?
Y
Y
BUS MASTER Tx
TA1 (T7:T0), TA2 (T15:T8)
BUS MASTER Rx
TA1 (T7:T0), TA2 (T15:T8),
AND E/S BYTE
DS2431-A1 SETS
SETS PF = 1
CLEARS AA = 0
SETS E2:E0 = T2:T0
DS2431-A1 SETS
SCRATCHPAD
BYTE COUNTER = T2:T0
MASTER Tx DATA BYTE
TO SCRATCHPAD
DS2431-A1
INCREMENTS
BYTE COUNTER
BUS MASTER Rx
DATA BYTE FROM
SCRATCHPAD
APPLIES ONLY
IF THE MEMORY
AREA IS NOT
PROTECTED.
IF WRITE PROTECTED,
THE DS2431-A1
COPIES THE DATE
BYTE FROM THE
TARGET ADDRESS
INTO THE SP.
DS2431-A1
INCREMENTS
E2:E0
Y
MASTER Tx RESET?
N
Y
MASTER Tx RESET?
N
IF IN EPROM MODE,
THE DS2431-A1
LOADS THE BITWISE
LOGICAL AND,
THE TRANSMITTED
BYTE, AND THE
DATA BYTE FROM
THE TARGETED
ADDRESS INTO
THE SP.
N
E2:E0 = 7?
Y
N
BYTE COUNTER
= E2:E0?
Y
N
BUS MASTER Rx CRC-16
OF COMMAND, ADDRESS,
E/S BYTE, DATA BYTES
T2:T0 = 0?
AS SENT BY THE DS2431-A1
Y
PF = 0
N
BUS MASTER
Rx "1"s
MASTER Tx RESET?
Y
DS2431-A1 Tx CRC-16 OF
COMMAND, ADDRESS,
DATA BYTES AS THEY
WERE SENT BY THE BUS
MASTER
N
BUS MASTER
Rx "1"s
MASTER Tx RESET?
Y
TO FIGURE 7
2ND PART
TO ROM FUNCTIONS
FLOW CHART (FIGURE 9)
Figure 7. Memory Function Flow Chart
_______________________________________________________________________________________
9
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
