sc16is850l NXP Semiconductors, sc16is850l Datasheet - Page 14

• Manufacturer Part Number: sc16is850l
• Description: Single Uart With I2c-bus/spi Interface, 128 Bytes Of Transmit And Receive Fifos, Irda Sir Built-in Support
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SC16IS850L
Product data sheet
7.9 Loopback mode
The internal loopback capability allows on-board diagnostics. In the Loopback mode, the
normal modem interface pins are disconnected and reconfigured for loopback internally
(see
In the Loopback mode, the transmitter output (TX) and the receiver input (RX) are
disconnected from their associated interface pins, and instead are connected together
internally. The CTS, DSR, CD, and RI are disconnected from their normal modem control
input pins, and instead are connected internally to RTS, DTR, MCR[3] (OP2) and MCR[2]
(OP1). Loopback test data is entered into the transmit holding register via the user data
bus interface, D[7:0]. The transmit UART serializes the data and passes the serial data to
the receive UART via the internal loopback connection. The receive UART converts the
serial data back into parallel data that is then made available at the user data interface
D[7:0]. The user optionally compares the received data to the initial transmitted data for
verifying error-free operation of the UART TX/RX circuits.
In this mode, the interrupt pin is 3-stated, therefore, the software must use the polling
method (see
Figure
8). MCR[3:0] register bits are used for controlling loopback diagnostic testing.
Section
All information provided in this document is subject to legal disclaimers.
8.2.2) to send and receive data.
Rev. 1 — 22 July 2011
Single UART with I
SC16IS850L
2
C-bus/SPI interface
© NXP B.V. 2011. All rights reserved.
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