Texas Instruments AM335 Series Technical Reference Manual

External
peripheral
...1_2..1_1..0_2..0_1
EVTx
Destination Address
Destination Address + 500h
Destination Address + A00h
...
...
Destination Address + 95100h
Destination Address + 95600h
Destination Address + 95B00h
479_640
478_640
477_640
478_639
479_639479_638......
...
...
...
...
2_640...
... 1_639 1_640
0_6400_6390_638......
...
...
...
...
...
...
0_30_2
1_21_1
0_1
2_1
478_1
479_1
477_1
479_2
478_2
479_3
www.ti.com Functional Description
11.3.19.4.2 Bursting Peripherals
Higher bandwidth applications require that multiple data elements be presented to the processor core for
every synchronization event. This frame of data can either be from multiple sources that are working
simultaneously or from a single high-throughput peripheral that streams data to/from the processor.
In this example, a port is receiving a video frame from a camera and presenting it to the processor one
array at a time. The video image is 640 × 480 pixels, with each pixel represented by a 16-bit element. The
image is to be stored in external memory. Figure 11-30 shows this example.
To transfer data from an external peripheral to an external buffer one array at a time based on EVTn ,
channel n must be configured. Due to the nature of the data (a video frame made up of arrays of pixels)
the destination is essentially a 2D entity. Figure 11-31 shows the parameters to service the incoming data
with a 1D-to-2D transfer using AB-synchronization. The source address is set to the location of the video
framer peripheral, and the destination address is set to the start of the data buffer. Because the input
address is static, the SRCBIDX is 0 (no modification to the source address). The destination is made up of
arrays of contiguous, linear elements; therefore, the DSTBIDX is set to pixel size, 2 bytes. ANCT is equal
to the pixel size, 2 bytes. BCNT is set to the number of pixels in an array, 640. CCNT is equal to the total
number of arrays in the block, 480. SRCCIDX is 0 because the source address undergoes no increment.
The DSTCIDX is equal to the difference between the starting addresses of each array. Because a pixel is
16 bits (2 bytes), DSTCIDX is equal to 640 × 2.
Figure 11-30. Servicing Peripheral Burst Example
925
SPRUH73H–October 2011–Revised April 2013 Enhanced Direct Memory Access (EDMA)
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Texas Instruments AM335 Series Specifications

General

Brand	Texas Instruments
Model	AM335 Series
Category	Computer Hardware
Language	English