DS2490 View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated

Part Name

Description

Manufacturer

DS2490

USB to 1-WireTM Bridge Chip

Dallas Semiconductor -> Maxim Integrated 

USB CONFIGURATION Figure 10

USB HOST

SYSTEM

SW

default pipe

DS2490 USB 1-WIRE DEVICE

1-WIRE INTERFACE

USB ENUMERATION

USB CONTROL

EP0 1-WIRE MODE

1-WIRE CONTROL

1-WIRE COMMUNICATION

DS2490

1-WIRE

CLIENT

interrupt pipe

bulk pipe

bulk pipe

USB PHYSICAL I/F

TOUCH DETECTION

EP1

DEVICE STATE

EP2

1-WIRE

EP3 DATA I/O

Endpoint (EP) Summary Description

EP0 is the endpoint for the bi-directional default control pipe. It is used for the USB enumeration

process, USB core request communication, and all DS2490 specific command communication.

EP1 is the endpoint for an interrupt pipe (Device to Host) and is used to relay DS2490 status register data

and specific command execution completion and/or error information to the host. It is also used to

inform the host of 1-Wire device-attach detection. The polling period requested for EP1 is either 10 mS

or 1 mS, depending on the alternate interface setting of the 1-Wire interface. The default polling period

for EP1 is 10 mS.

EP2 is an endpoint for a bulk data out pipe (Data from Host) and is used to transmit 1-Wire device data

from the host to the DS2490. The information received at this endpoint will be transmitted as data on the

1-Wire bus.

EP3 is an endpoint for a bulk data in pipe (Data to Host) and is used to send data received by the DS2490

from the 1-Wire bus back to the host for processing.

1-Wire Interface Summary Description

The interface is the USB collection point for the four endpoints. Four alternate settings exist for the 1-

Wire interface which correspond to different operational modes for the pipes to EP1, EP2, and EP3. As

shown in Table 2, the alternate settings specify different polling periods for the interrupt pipe and

different maximum packet sizes for the two bulk pipes.

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