XR21V1410IL-0A-EB Datasheet, PDF (8/28 Pages) Exar Corporation – 1-CH FULL-SPEED USB UART

XR21V1410
1-CH FULL-SPEED USB UART
FIGURE 3. RECEIVE DATA FORMAT
REV. 1.3.0
1st byte
2nd byte
1st byte
2nd byte
7 or 8 bit mode
76543210
x x x x OF B P
9 bit mode
76543210
7 = ‘0’ in 7 bit mode
P = Parity Error (= ‘0’ if not enabled)
B = Break
F = Framing Error
O = Overrun Error
x = ‘0’
x x x x OF B 8
B = Break
F = Framing Error
O = Overrun Error
x = ‘0’
Error flags are also available from the ERROR_STATUS register and the interrupt packet, however these flags
are historical flags indicating that an error has occurred since the previous read of the status register.
Therefore, no conclusion can be drawn as to which specific byte(s) may have contained an actual error in this
manner.
1.5.3 GPIO
There are 6 GPIOs. By default, the GPIOs are general purpose I/Os. However, there are few modes that can
be enabled to add additional feature such as Auto RTS/CTS Flow control, Auto DTR/DSR Flow Control or
Transceiver Enable Control. See Table 14.
1.5.4 Automatic RTS/CTS Hardware Flow Control
GPIO5 and GPIO4 of the UART channel can be enabled as the RTS# and CTS# signals for Auto RTS/CTS
flow control when GPIO_MODE[2:0] = ’001’ and FLOW_CONTROL[2:0] = ’001’. Automatic RTS flow control is
used to prevent data overrun errors in local RX FIFO by de-asserting the RTS signal to the remote UART.
When there is room in the RX FIFO, the RTS pin will be re-asserted. Automatic CTS flow control is used to
prevent data overrun to the remote RX FIFO. The CTS# input is monitored to suspend/restart the local
transmitter (see Figure 4):
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