
ADSP-BF59x Blackfin Processor Hardware Reference
11-5
UART Port Controllers
Description of Operation
The following sections describe the operation of the UART.
UART Transfer Protocol
UART communication follows an asynchronous serial protocol, consisting
of individual data words. A word has 5 to 8 data bits.
All data words require a start bit and at least one stop bit. With the
optional parity bit, this creates a 7- to 12-bit range for each word. The for-
mat of received and transmitted character frames is controlled by the line
control register (
UART_LCR
). Data is always transmitted and received least
significant bit (LSB) first.
Figure 11-2 on page 11-6
shows a typical physical bitstream measured on
one of the TX pins.
Aside from the standard UART functionality, the UART also supports
half-duplex serial data communication via infrared signals, according to
the recommendations of the Infrared Data Association (IrDA). The physi-
cal layer known as IrDA SIR (9.6/115.2 Kbps rate) is based on
return-to-zero-inverted (RZI) modulation. Pulse position modulation is
not supported.
Using the 16× data rate clock, RZI modulation is achieved by inverting
and modulating the non-return-to-zero (NRZ) code normally transmitted
by the UART. On the receive side, the 16× clock is used to determine an
IrDA pulse sample window, from which the RZI-modulated NRZ code is
recovered.
IrDA support is enabled by setting the
IREN
bit in the
UART_GCTL
register.
The IrDA application requires external transceivers.
Содержание ADSP-BF59x Blackfin
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