ADSP-BF526_15 Datasheet, PDF (13/88 Pages) Analog Devices – Blackfin Embedded Processor

ADSP-BF522/ADSP-BF523/ADSP-BF524/ADSP-BF525/ADSP-BF526/ADSP-BF527
Each general-purpose port pin can be individually controlled by
manipulation of the port control, status, and interrupt registers:
• GPIO direction control register — Specifies the direction of
each individual GPIO pin as input or output.
• GPIO control and status registers — The processor
employs a “write one to modify” mechanism that allows
any combination of individual GPIO pins to be modified in
a single instruction, without affecting the level of any other
GPIO pins. Four control registers are provided. One regis-
ter is written in order to set pin values, one register is
written in order to clear pin values, one register is written
in order to toggle pin values, and one register is written in
order to specify a pin value. Reading the GPIO status regis-
ter allows software to interrogate the sense of the pins.
• GPIO interrupt mask registers — The two GPIO interrupt
mask registers allow each individual GPIO pin to function
as an interrupt to the processor. Similar to the two GPIO
control registers that are used to set and clear individual
pin values, one GPIO interrupt mask register sets bits to
enable interrupt function, and the other GPIO interrupt
mask register clears bits to disable interrupt function.
GPIO pins defined as inputs can be configured to generate
hardware interrupts, while output pins can be triggered by
software interrupts.
• GPIO interrupt sensitivity registers — The two GPIO inter-
rupt sensitivity registers specify whether individual pins are
level- or edge-sensitive and specify—if edge-sensitive—
whether just the rising edge or both the rising and falling
edges of the signal are significant. One register selects the
type of sensitivity, and one register selects which edges are
significant for edge-sensitivity.
PARALLEL PERIPHERAL INTERFACE (PPI)
The processor provides a parallel peripheral interface (PPI) that
can connect directly to parallel analog-to-digital and digital-to-
analog converters, video encoders and decoders, and other gen-
eral-purpose peripherals. The PPI consists of a dedicated input
clock pin, up to three frame synchronization pins, and up to 16
data pins. The input clock supports parallel data rates up to half
the system clock rate, and the synchronization signals can be
configured as either inputs or outputs.
The PPI supports a variety of general-purpose and ITU-R 656
modes of operation. In general-purpose mode, the PPI provides
half-duplex, bidirectional data transfer with up to 16 bits of
data. Up to three frame synchronization signals are also pro-
vided. In ITU-R 656 mode, the PPI provides half-duplex
bidirectional transfer of 8- or 10-bit video data. Additionally,
on-chip decode of embedded start-of-line (SOL) and start-of-
field (SOF) preamble packets is supported.
General-Purpose Mode Descriptions
The general-purpose modes of the PPI are intended to suit a
wide variety of data capture and transmission applications.
Three distinct submodes are supported:
1. Input mode — Frame syncs and data are inputs into the
PPI.
2. Frame capture mode — Frame syncs are outputs from the
PPI, but data are inputs.
3. Output mode — Frame syncs and data are outputs from
the PPI.
Input Mode
Input mode is intended for ADC applications, as well as video
communication with hardware signaling. In its simplest form,
PPI_FS1 is an external frame sync input that controls when to
read data. The PPI_DELAY MMR allows for a delay (in PPI_-
CLK cycles) between reception of this frame sync and the
initiation of data reads. The number of input data samples is
user programmable and defined by the contents of the
PPI_COUNT register. The PPI supports 8-bit and 10-bit
through 16-bit data, programmable in the PPI_CONTROL
register.
Frame Capture Mode
Frame capture mode allows the video source(s) to act as a slave
(for frame capture for example). The ADSP-BF52x processors
control when to read from the video source(s). PPI_FS1 is an
HSYNC output, and PPI_FS2 is a VSYNC output.
Output Mode
Output mode is used for transmitting video or other data with
up to three output frame syncs. Typically, a single frame sync is
appropriate for data converter applications, whereas two or
three frame syncs could be used for sending video with hard-
ware signaling.
ITU-R 656 Mode Descriptions
The ITU-R 656 modes of the PPI are intended to suit a wide
variety of video capture, processing, and transmission applica-
tions. Three distinct submodes are supported:
1. Active video only mode
2. Vertical blanking only mode
3. Entire field mode
Active Video Mode
Active video only mode is used when only the active video por-
tion of a field is of interest and not any of the blanking intervals.
The PPI does not read in any data between the end of active
video (EAV) and start of active video (SAV) preamble symbols,
or any data present during the vertical blanking intervals. In this
mode, the control byte sequences are not stored to memory;
they are filtered by the PPI. After synchronizing to the start of
Field 1, the PPI ignores incoming samples until it sees an SAV
code. The user specifies the number of active video lines per
frame (in PPI_COUNT register).
Vertical Blanking Interval Mode
In this mode, the PPI only transfers vertical blanking interval
(VBI) data.
Rev. D | Page 13 of 88 | July 2013