DS2433 Maxim, DS2433 Datasheet - Page 16

• Manufacturer Part Number: DS2433
• Description: The DS2433 4Kb 1-Wire® EEPROM identifies and stores relevant information about the product to which it is associated
• Manufacturer: Maxim

DS2433
1-Wire SIGNALING
The DS2433 requires strict protocols to insure data integrity. The protocol consists of four types of
signaling on one line: Reset Sequence with Reset Pulse and Presence Pulse, Write 0, Write 1 and Read
Data. All these signals except Presence Pulse are initiated by the bus master. The DS2433 can
communicate at two different speeds, regular speed and Overdrive Speed. If not explicitly set into the
overdrive mode, the DS2433 will communicate at regular speed. While in Overdrive Mode the fast timing
applies to all wave forms.
The initialization sequence required to begin any communication with the DS2433 is shown in Figure 10.
A Reset Pulse followed by a Presence Pulse indicates the DS2433 is ready to send or receive data given
the correct ROM command and memory function command. The bus master transmits (Tx) a Reset Pulse
(t
, minimum 480s at regular speed, 48s at Overdrive Speed). The bus master then releases the line
RSTL
and goes into receive mode (Rx). The 1-Wire bus is pulled to a high state via the pullup resistor. After
detecting the rising edge on the data pin, the DS2433 waits (t
, 15-60s at regular speed, 2-6s at
PDH
Overdrive speed) and then transmits the Presence Pulse (t
, 60-240s at regular speed, 8-24s at
PDL
Overdrive Speed).
A Reset Pulse of 480s or longer will exit the Overdrive Mode returning the device to regular speed. If
the DS2433 is in Overdrive Mode and the Reset Pulse is no longer than 80s the device will remain in
Overdrive Mode.
READ/WRITE TIME SLOTS
The definitions of write and read time slots are illustrated in Figure 11. All time slots are initiated by the
master driving the data line low. The falling edge of the data line synchronizes the DS2433 to the master
by triggering a delay circuit in the DS2433. During write time slots, the delay circuit determines when the
DS2433 will sample the data line. For a read data time slot, if a “0” is to be transmitted, the delay circuit
determines how long the DS2433 will hold the data line low overriding the 1 generated by the master. If
the data bit is a “1,” the device will leave the read data time slot unchanged.
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