XR21V1414_10 Datasheet, PDF (9/32 Pages) Exar Corporation – 4-CH FULL-SPEED USB UART

XR21V1414
REV. 1.1.0
4-CH FULL-SPEED USB UART
1.0 FUNCTIONAL DESCRIPTIONS
1.1 USB interface
The USB interface of the V1414 is compliant with the USB 2.0 Full-Speed Specifications. The USB
configuration model presented by the V1414 to the device driver is compatible to the Abstract Control Model of
the USB Communication Device Class (CDC-ACM). The V1414 uses the following set of parameters:
• 1 Control Endpoint
s Endpoint 0 as outlined in the USB specifications
• 1 Configuration is supported
• 2 interfaces per UART channel
s Each UART channel has a single interrupt endpoint
s Each UART channel have bulk-in and bulk-out endpoints
1.1.1 USB Vendor ID
Exar’s USB Vendor ID is 0x04E2. This is the default Vendor ID that is used for the V1414 unless a valid
EEPROM is present on the I2C interface signals. If a valid EEPROM is present, the Vendor ID from the
EEPROM will be used.
1.1.2 USB Product ID
The default USB Product ID for the V1414 is 0x1414. If a valid EEPROM is present, the Product ID from the
EEPROM will be used.
1.2 USB Device Driver
The V1414 device can be used with either a standard CDC-ACM driver or a custom driver. When the CDC-
ACM driver is used, the driver has no knowledge of the V1414 device registers. Because of this, the V1414
device is initialized to the following settings:
TABLE 1: V1414 REGISTER DEFAULTS WITH CDC-ACM DRIVER
REGISTER
VALUE
NOTES
FLOW_CONTROL
0x01
Hardware flow control
GPIO_MODE
0x01
RTS / CTS flow control
GPIO_DIRECTION
0x08
DTR configured as an output (in addition to RTS which is set by
GPIO_MODE)
GPIO_INT_MASK
0x30
CD and DSR are interrupt sensitive, i.e. can cause a USB inter-
rupt to be generated
9