DS24B33 Maxim, DS24B33 Datasheet - Page 12

• Manufacturer Part Number: DS24B33
• Description: The DS24B33 is a 4096-bit, 1-Wire® EEPROM organized as 16 memory pages of 256 bits each
• Manufacturer: Maxim

1-Wire 4Kb EEPROM
The Read Memory command is the general function to
read from the DS24B33. After issuing the command,
the master must provide a 2-byte target address, which
should be in the range of 0000h to 01FFh. If the target
address is higher than 01FFh, the DS24B33 changes
the upper 7 address bits to 0. After the address is
transmitted, the master reads data starting at the (modi-
fied) target address and can continue until address
01FFh. If the master continues reading, the result is
FFh. The Read Memory command can be ended at any
point by issuing a reset pulse. Note that the (modified)
target address provided with the Read Memory com-
mand overwrites the target address that was specified
with a previously issued Write Scratchpad command.
The Read Memory command overwrites the scratchpad
with data from the target memory page. When reading
the last byte of a memory page, the scratchpad is
loaded with data from the next memory page. This
could cause unexpected data to be loaded into the
scratchpad.
Figure 8. Hardware Configuration
12
______________________________________________________________________________________
Rx
Tx
BUS MASTER
Read Memory [F0h]
OPEN-DRAIN
PORT PIN
Tx = TRANSMIT
Rx = RECEIVE
V
PUP
R
PUP
The 1-Wire bus is a system that has a single bus master
and one or more slaves. In all instances the DS24B33 is
a slave device. The bus master is typically a microcon-
troller. The discussion of this bus system is broken
down into three topics: hardware configuration, trans-
action sequence, and 1-Wire signaling (signal types
and timing). The 1-Wire protocol defines bus transac-
tions in terms of the bus state during specific time slots,
which are initiated on the falling edge of sync pulses
from the bus master.
The 1-Wire bus has only a single line by definition; it is
important that each device on the bus be able to drive
it at the appropriate time. To facilitate this, each device
attached to the 1-Wire bus must have open-drain or
three-state outputs. The 1-Wire port of the DS24B33 is
open drain with an internal circuit equivalent to that
shown in Figure 8.
DATA
I
L
DS24B33 1-Wire PORT
Hardware Configuration
100Ω MOSFET
1-Wire Bus System
Rx
Tx