DS2480 Dallas Semiconducotr, DS2480 Datasheet - Page 6

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

COMMUNICATION COMMAND CODES Table 1
COMMUNICATION COMMAND RESPONSE Table 2
(The Search Accelerator Control command does not generate a response byte.)
Reset
The Reset command must be used to begin all 1–Wire
communication. The speed selection included in the
command code immediately takes effect. The response
byte includes a code for the reaction on the 1–Wire bus
(bits 0 and 1) and a code for the chip revision (bits 2 to 4).
If bit 5 of the response byte reads ‘1’, a programming
voltage is present on the V
may try programming EPROM devices.
Single Bit
The Single Bit command is used to generate a single
time slot on the 1–Wire bus at the speed indicated by
bits 2 and 3. The type of the time slot (write zero or write
one) is determined by the logic value of bit 4. A read data
time slot is identical to the write one time slot. Bits 0 and
1 of the response byte transmitted by the DS2480 at the
DS2480
042498 6/26
Single Bit
Search
Accelerator
Control
Reset
Pulse
Single Bit
Reset
Pulse
FUNCTION
FUNCTION
BIT 7
BIT 7
1
1
1
1
1
1
1
BIT 6
PP
BIT 6
0
0
1
1
0
1
1
pin, indicating that one
BIT 5
BIT 5
Text
0
1
0
1
See
0
1
0 = write 0
1 = write 1
0 = accelerator off
1 = accelerator on
See Text
(don’t care)
0 = 5V strong pull–up
1 = 12V prog. pulse
BIT 4
0
BIT 4
same as sent
same as sent
end of the time slot reveal the value found on the 1–Wire
bus when reading.
For a time slot without a subsequent strong pull–up, bit 1
of the command must be set to 0. For a time slot immedi-
ately followed by a strong pull–up bit 1 must be set to 1.
As soon as the strong pull–up is over, the device will
send a second response byte, code EFh (read 1) or ECh
(read 0), depending on the value found on the 1–Wire
bus when reading. The strong pull–up directly following
the single bit is used in conjunction with the Crypto
iButton.
Search Accelerator Control
The Search Accelerator Control command is used to set
or reset the Search Accelerator control flag. Bit 4 of the
command code contains the state to which the acceler-
BIT 3
1
00
01
10
11
00
01
10
11
00
01
10
11
11
BIT 2
0
BIT 3, BIT 2
reg. speed
flex. speed
OD. speed
reg. speed
reg. speed
flex. speed
OD. speed
reg. speed
pulse
reg. speed
flex. speed
OD. speed
reg. speed
1–Wire read back,
both bits same value
00 = 1–Wire shorted
01 = presence pulse
10 = alarming presence
11 = no presence pulse
BIT 1
pulse
undefined
See Text
See Text
BIT 1
0
0
BIT 0
BIT 0
1
1
1
1