17-2 Intel® PXA26x Processor Family Developer’s Manual
Hardware UART
17.2 Features
The HWUART has the following features:
•Functionally compatible with the 16550A and 16750 UART specifications. The UART
supports not only the 16550A and 16750 industry standards but these additional functions as
well:
— DMA requests for transmit and receive data services
— Slow infrared asynchronous interface
— Non-Return-to-Zero (NRZ) encoding/decoding function
— 64 byte transmit/receive FIFO buffers
— Programmable receive FIFO trigger thre shold
— Auto baud-rate detection
— Auto flow
•Ability to add or delete standard asynchronous communications bits (start, stop, and parity) in
the serial data
•Independently controlled transmit, receive, line status, and data set interrupts
•Programmable baud rate generator that allows the internal clock to be divided by 1 to 216–1 to
generate an internal 16X clock
•Modem control functions (nCTS, nRTS)
•Autoflow capability controls data I/O without generating Interrupts:
— nRTS (output) controlled by UAR T Receiver FIFO
— nCTS (input) from modem controls UART transmitter
•Fully programmable serial-interface:
— 5-, 6-, 7-, or 8-bit characters
— Even, odd, and no parity detection
— 1, 1.5, or 2 stop bit generation
— Baud rate generation up to 921.6Kbps
— False start bit detection.
•64-byte transmit FIFO
•64-byte receive FIFO
•Complete status reporting capability
•Ability to generate and detect line breaks
•Internal diagnostic capabilities that include:
— Loopback controls for communications link fault isolation
— Break, parity, and framing error sim ulation
•Fully prioritized interrupt system controls
•Separate DMA requests for transmit and receive data services