XR21B1421 Datasheet, PDF (18/50 Pages) Exar Corporation – Enhanced 1-Ch Full-Speed

XR21B1421
The SUSPEND_STATE field will set or clear the GPIO pin and the SUSPEND_MODE field will configure any GPIO output
as open drain or push-pull output. Refer to “GET / SET_PIN_CONFIG” on page 41 or “GET / SET_SUSPEND_OUTPUT_-
CONFIG” on page 31. Configuration using the SET_SUSPEND_OUTPUT_CONFIG report will be lost at the next power
cycle or bus reset of the device. Configuration using the SET_PIN_CONFIG report will be permanent.
TXT and RXT Pins
The Transmit toggle and Receive toggle pins "toggle" at a rate of approximately 10 Hz whenever the UART transmit and
receive pins (respectively) are active.
OTP
The OTP is an on-chip non-volatile memory, that is incrementally one-time programmable via the USB interface. Some bits
are pre-programmed at the factory and caution must be taken not to program any locations except those user defined
addresses given in this data sheet. Some of the HID reports result in irreversible programming of the OTP. Once a specific
report programs a portion of the OTP, the lock bit for that section of the OTP will be set and further changes to that section
will not be allowed. Note that all OTP writes will take immediate effect, except for setting the global lock bit (report 0x68),
which requires a hardware or power on reset to take effect.
© 2014 Exar Corporation
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