MCIMX281AVM4B Freescale Semiconductor, MCIMX281AVM4B Datasheet - Page 2124

• Manufacturer Part Number: MCIMX281AVM4B
• Description: IC MPU I.MX28 1.2 289MAPBGA
• Manufacturer: Freescale Semiconductor
• Series: i.MX28r

Specifications of MCIMX281AVM4B

• Core Processor: ARM9
• Core Size: 32-Bit
• Speed: 454MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, MMC, SmartCard, SPI, SSI, UART/USART, USB OTG
• Peripherals: DMA, I²S, LCD, POR, PWM, WDT
• Program Memory Size: 128KB (32K x 32)
• Program Memory Type: Mask ROM
• Ram Size: 32K x 32
• Voltage - Supply (vcc/vdd): 1.25 V ~ 5.25 V
• Data Converters: A/D 17x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 289-LFBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Eeprom Size: -
• Lead Free Status / Rohs Status: Supplier Unconfirmed

Operation
34.2.3 Scaling
The PXP can scale YUV images from 1/4x to about 4096x using a bilinear scaling algorithm.
The hardware is capable of scaling with 12-bit fractional resolution, or in 1/4096
increments with independent scaling ratios for the X and Y direction. The scaler also
implements an initial offset, which can be useful when scaling by powers of 2 in order to
ensure that the resulting pixels are averages (select ½ pixel offset) of the source pixels
instead of producing a decimated or replicated image. Also, the offset can be used to achieve
per pixel addressing on the input source image.
The scaling parameter is specified to the hardware in terms of the inverse of the scaling
ratio desired. This can also be viewed as the step size between computed sample values.
For instance, when scaling by 2x the inverse is 1/2, therefore the scaler will increment by
1/2 pixel steps across the input image and compute the bilinear average for each sample
point.
The scaling values are represented by 12-bit fractional values in the scaling register and
hardware. The scaling ratios are computed as the input size divided by the output size. The
resulting decimal value must then be converted into a 12-bit fixed point value by multiplying
by 2
To scale an image from 400x300 to 320x200, the horizontal XSCALE factor is computed
as
XSCALE =
The vertical YSCALE can be similarly computed as
YSCALE =
The scaler will use the CROP_XBASE and CROP_YBASE values as an offset into the
source S0 image for the origin of the input image to be scaled. The CROP_WIDTH and
CROP_HEIGHT parameters will be used to determine the extent of the scaled image in the
output buffer. It is tempting to view the cropping width and height as being applied to the
input buffer, but this is incorrect -- the PXP uses these values as a mask on the output buffer
to determine which regions of the output buffer require data from the scaled input image.
To enable scaling, the HW_PXP_CTRL_SCALE bit must be set and the desired scaling
ratios written into the HW_PXP_S0SCALE registers. Initial offsets should be programmed
into the HW_PXP_S0OFFSET register.
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12
or 4096 to produce the value programmed into the scaling registers.
OutputSize
OutputSize
InputSize
InputSize
× 4096 =
× 4096 =
i.MX28 Applications Processor Reference Manual, Rev. 1, 2010
400
320
300
200
× 4096 = 5120 × 4096 = 0x0140 _ 0000
× 4096 = 6144 × 4096 = 0x0180 _ 0000
Freescale Semiconductor, Inc.
th
pixel