DS2490Y Maxim Integrated Products, DS2490Y Datasheet - Page 23

• Manufacturer Part Number: DS2490Y
• Description: IC BRIDGE CLIP USB TO 1-W 24SOIC
• Manufacturer: Maxim Integrated Products

Specifications of DS2490Y

• Applications: USB
• Interface: 1-Wire
• Voltage - Supply: 3 V ~ 5.5 V
• Package / Case: 24-SOIC (7.5mm Width)
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

READ STRAIGHT—This command transmits a user-specified preamble of data to the 1-Wire bus and
then reads back as many bytes as specified. The preamble typically consists of a 1-Wire command code
followed by TA1 and TA2. It is possible to include a Match ROM command and ROM ID in the
preamble to also address a device at the current speed. This command can also be used to copy the
scratchpad or disconnect a path. Embedded command bit RST enables a 1-Wire reset before the
command executes. The EP2 FIFO must be pre-filled with preamble data before command execution.
Additionally, for preamble sizes greater then the FIFO size, the FIFO content status must be monitored by
host SW so that additional data can be sent to the FIFO when necessary. A similar EP3 FIFO content
monitoring requirement exists for the block read. During a block read, the number of bytes loaded into
the EP3 FIFO must be monitored so that the data can be read before the FIFO overflows.
DO & RELEASE—This command is typically used to control the activity of the CPU of the crypto
iButton, which requires a release sequence. This command can also be used to read from or write to the
I/O buffer or Status Register of the crypto iButton. A short preamble (3 bytes) consists of a 1-Wire
command code followed by the release sequence. A four-byte preamble with embedded command bit R
= 1 consists of a 1-Wire command code followed by length byte and the release sequence. A 4-byte
preamble with embedded command bit R = 0 consists of a 1-Wire command code followed by a status
byte and the release sequence. The long preamble (minimum 5 bytes, embedded command bit R = 0)
consists of a 1-Wire command, a length byte, data bytes and the release sequence. In this case, the length
byte indicates the total number of bytes between the length byte and release sequence. The least
significant byte of the release sequence is transmitted first. Embedded command bit SPU must be 1 when
trying to run (start, continue) the CPU of the crypto iButton. In all other cases, SPU should be 0.
Additionally, embedded command bit F can be used to clear the communication command buffer and
EP2/3 FIFOs if an error occurs during execution of the command. The EP2 FIFO must be pre-filled with
preamble data before command execution. Additionally, for preamble sizes greater then the FIFO size,
Command parameters:
EP2 data:
EP3 data:
Result Register:
Command parameters:
EP2 data:
EP3 data:
Result Register:
2 bytes: match command byte, new 1-Wire speed byte (optional).
Length
8 bytes
None
If ICP = 1: no result data is generated.
If ICP = 0 and NTF = 1: a result value of 0x00 will be generated.
If IPC = 0 and NTF = 0: no result data is generated since there are no
error codes associated with this command.
3 bytes: 2-byte parameter specifying block read size, byte specifying
preamble size.
Length
Same as
preamble size
Length
Same as block
size
If ICP = 1: no result data is generated.
If ICP = 0 and NTF = 1: a result value of 0x00 will be generated.
If IPC = 0 and NTF = 0: no result data is generated since there are no
error codes associated with this command.
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ROM ID of the device to be accessed.
Preamble data to be written to the 1-Wire device.
Data block read from the 1-Wire device.
Description
Description
Description