XR21V1412_10 Datasheet, PDF (8/30 Pages) Exar Corporation – 2-CH FULL-SPEED USB UART

XR21V1412
2-CH FULL-SPEED USB UART
REV. 1.1.0
1.3 I²C Interface
The I²C interface provides connectivity to an external I²C memory device (i.e. EEPROM) that can be read by
the V1412 for configuration.
The SDA and SCL are used to specify whether Remote Wakeup and/or Bus Powered configurations are to be
supported. These pins are sampled at power-up. The following table describes how Remote Wakeup and Bus
Powered support.
TABLE 2: REMOTE WAKEUP AND POWER MODES
SDA
SCL
REMOTE WAKE-UP
SUPPORT
POWER MODE
1
1
No
Self-Powered
1
0
No
Bus-Powered
0
1
Yes
Self-Powered
0
0
Yes
Bus-Powered
1.3.1 EEPROM Contents
The I²C address should be 0xA0. An EEPROM can be used to override default Vendor IDs and Device IDs, as
well as other attributes and maximum power consumption. The EEPROM must contain 8 bytes of data as
specified in Table 3
TABLE 3: EEPROM CONTENTS
EEPROM
ADDRESS
CONTENTS
0
Vendor ID (LSB)
1
Vendor ID (MSB)
2
Product ID (LSB)
3
Product ID (MSB)
4
Device Attributes
5
Device Maximum Power
6
Reserved
7
Signature of 0x58 (’X’). If the signature is not correct, the contents of the EEPROM are ignored.
These values are uploaded from the EEPROM to the corresponding USB Standard Device Descriptor or
Standard Configuration Descriptor. For details of the USB Descriptors, refer to the USB 2.0 specifications.
1.3.1.1 Vendor ID
The Vendor ID value replaces the idVendor field in the USB Standard Device Descriptor.
1.3.1.2 Product ID
The Product ID value replaces the idProduct field in the USB Standard Device Descriptor.
1.3.1.3 Device Attributes
The Device Attributes value replaces the bmAttributes field in the USB Standard Configuration Descriptor. The
default setting in the V1412 device is 0xA0. The bit field definitions are:
• Bit 7 is reserved - set to ’1’
8