DS2480 Dallas Semiconducotr, DS2480 Datasheet - Page 19

• Manufacturer Part Number: DS2480
• Description: Serial 1.Wire Line Driver
• Manufacturer: Dallas Semiconducotr

SOFTWARE DRIVER EXAMPLES
The DS2480 requires a software driver that translates
the activities to be generated on the 1–Wire bus into the
appropriate commands. The examples below cover typ-
ical situations, such as reading the ROM, writing to the
scratchpad of a Memory iButton, reading the memory of
a Memory iButton, programming an Add–Only iButton
EPROM and performing a temperature conversion with
the Temperature iButton DS1920. An example for the
use of the Search Accelerator is included in the descrip-
tion of the Search Accelerator, earlier in this document.
The DS2480 command codes used in these examples
are valid for regular speed and will work properly on
short 1–Wire busses (< 10 meters). The response byte
on the reset command assumes a normal presence
pulse, no alarm or short.
The DS2480 includes a 1–byte buffer that stores a byte
received from the host while the previous byte is being
translated into activity on the 1–Wire bus. For this rea-
son the host may send another byte even without having
received the response byte. Sending bytes faster than
they can be translated into 1–Wire activities may result
in loss of data and/or synchronization and therefore
should be avoided.
READ ROM SEQUENCE
Generate Reset Pulse
Set data mode
Read ROM Command
Read ROM ID (8 bytes)
Set command mode
Generate Reset Pulse
Action Sequence
Host TX
FF (x8)
C1
C1
E1
33
E3
(nothing)
(nothing)
Host RX
(as sent)
ROM ID
C9
C9
WRITE SCRATCHPAD SEQUENCE
Write 2 bytes to scratchpad at memory locations 16h
and 17h
READ MEMORY SEQUENCE
Read 8 bytes from memory address 0040h
Generate Reset Pulse
Set data mode
Skip ROM Command
Write Scratchpad Cmd.
Starting Address TA1
Starting Address TA2
Write to the Scratchpad
Set command mode
Generate Reset Pulse
Generate Reset Pulse
Set data mode
Skip ROM Command
Read Memory Command
Starting Address TA1
Starting Address TA2
Read 8 bytes of data
Set command mode
Generate Reset Pulse
Action Sequence
Action Sequence
Host TX
(2 bytes)
Host TX
FF (x8)
CC
CC
C1
E1
E3
C1
C1
E1
E3
C1
0F
16
00
F0
40
00
042498 19/26
(nothing)
(nothing)
(nothing)
(nothing)
Host RX
(as sent)
(as sent)
(as sent)
(as sent)
Host RX
(as sent)
(as sent)
(as sent)
(as sent)
data
CC
DS2480
C9
C9
C9
C9