ADSP-BF531/ADSP-BF532
• Interrupts – Each transmit and receive port generates an
interrupt upon completing the transfer of a data-word or
after transferring an entire data buffer or buffers
through DMA.
TIMERS
There are four general-purpose programmable timer units in
the ADSP-BF531/ADSP-BF532 processor. Three timers have an
external pin that can be configured either as a pulse-width mod-
ulator (PWM) or timer output, as an input to clock the timer, or
as a mechanism for measuring pulse widths and periods of
external events. These timers can be synchronized to an external
clock input to the PF1 pin, an external clock input to the
PPI_CLK pin, or to the internal SCLK.
• Multichannel capability – Each SPORT supports 128 chan-
nels out of a 1,024-channel window and is compatible with
the H.100, H.110, MVIP-90, and HMVIP standards.
An additional 250 mV of SPORT input hysteresis can be
enabled by setting Bit 15 of the PLL_CTL register. When this bit
is set, all SPORT input pins have the increased hysteresis.
The timer units can be used in conjunction with the UART to
measure the width of the pulses in the data stream to provide an
autobaud detect function for a serial channel.
SERIAL PERIPHERAL INTERFACE (SPI) PORT
The ADSP-BF531/ADSP-BF532 processor has an SPI-compati-
ble port that enables the processor to communicate with
multiple SPI-compatible devices.
The timers can generate interrupts to the processor core provid-
ing periodic events for synchronization, either to the system
clock or to a count of external signals.
The SPI interface uses three pins for transferring data: two data
pins (master output-slave input, MOSI, and master input-slave
output, MISO) and a clock pin (serial clock, SCK). An SPI chip
select input pin (SPISS) lets other SPI devices select the proces-
sor, and seven SPI chip select output pins (SPISEL7–1) let the
processor select other SPI devices. The SPI select pins are recon-
figured programmable flag pins. Using these pins, the SPI port
provides a full-duplex, synchronous serial interface which sup-
ports both master/slave modes and multimaster environments.
In addition to the three general-purpose programmable timers,
a fourth timer is also provided. This extra timer is clocked by the
internal processor clock and is typically used as a system tick
clock for generation of operating system periodic interrupts.
SERIAL PORTS (SPORTs)
The ADSP-BF531/ADSP-BF532 processor incorporates two
dual-channel synchronous serial ports (SPORT0 and SPORT1)
for serial and multiprocessor communications. The SPORTs
support the following features:
The baud rate and clock phase/polarities for the SPI port are
programmable, and it has an integrated DMA controller, con-
figurable to support transmit or receive data streams. The SPI
DMA controller can only service unidirectional accesses at any
given time.
• I2S capable operation.
• Bidirectional operation – Each SPORT has two sets of inde-
pendent transmit and receive pins, enabling eight channels
of I2S stereo audio.
The SPI port clock rate is calculated as:
• Buffered (8-deep) transmit and receive ports – Each port
has a data register for transferring data words to and from
other processor components and shift registers for shifting
data in and out of the data registers.
fSCLK
SPI Clock Rate = --------------------------------
2 × SPI_Baud
Where the 16-bit SPI_Baud register contains a value of 2 to
65,535.
• Clocking – Each transmit and receive port can either use an
external serial clock or generate its own, in frequencies
ranging from (fSCLK/131,070) Hz to (fSCLK/2) Hz.
During transfers, the SPI port simultaneously transmits and
receives by serially shifting data in and out on its two serial data
lines. The serial clock line synchronizes the shifting and sam-
pling of data on the two serial data lines.
• Word length – Each SPORT supports serial data words
from 3 bits to 32 bits in length, transferred most-signifi-
cant-bit first or least-significant-bit first.
UART PORT
• Framing – Each transmit and receive port can run with or
without frame sync signals for each data word. Frame sync
signals can be generated internally or externally, active high
or low, and with either of two pulse widths and early or late
frame sync.
The ADSP-BF531/ADSP-BF532 processor provides a full-
duplex universal asynchronous receiver/transmitter (UART)
port, which is fully compatible with PC-standard UARTs. The
UART port provides a simplified UART interface to other
peripherals or hosts, supporting full-duplex, DMA-supported,
asynchronous transfers of serial data. The UART port includes
support for 5 data bits to 8 data bits, 1 stop bit or 2 stop bits, and
none, even, or odd parity. The UART port supports two modes
of operation:
• Companding in hardware – Each SPORT can perform
A-law or µ-law companding according to ITU recommen-
dation G.711. Companding can be selected on the transmit
and/or receive channel of the SPORT without additional
latencies.
• PIO (programmed I/O) – The processor sends or receives
data by writing or reading I/O-mapped UART registers.
The data is double-buffered on both transmit and receive.
• DMA operations with single-cycle overhead – Each SPORT
can automatically receive and transmit multiple buffers of
memory data. The processor can link or chain sequences of
DMA transfers between a SPORT and memory.
• DMA (direct memory access) – The DMA controller trans-
fers both transmit and receive data. This reduces the
number and frequency of interrupts required to transfer
Rev. D
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Page 10 of 60
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August 2006
ADI [ ADI ]
