ViewSonic VE510+-1 Service Manual page 22

Host Interface Control
Host interface controller is an interface between Mascot V and an external CPU. The access
to Mascot V internal internal registers, SRAM, programmable fonts, gamma tables, and ROM
is performed by interface controller. Mascot V provides single read/write and incremental
read/write. Mascot V supports I2C bus and SPI protocols. The bus protocol selection is
determined by pin CONFIG[4], and Mascot V slave address is determined by pin
CONFIG[3:0].
GPIO (General Purpose Input/Output)
Gerenal Purpose Input/Output
Mascot V has provided three pins for general purpose input/output(GPIO) pins; these pins can
be programmed as input or output pins; each GPIO pin has three registers for programming:
GPIO Input/output control register, GPIO output data register and GPIO input register; When
GPIO is programmed as output pin, GPIO Input/output control register is programmed as I
(output), and the output data is provided by GPIO output data register; When programmed as
input pin, GPIO Input/output control register is programmed as 0(input), the input value can be
accessed thrugh GPIO input register.
PWM (Pulse Width Modulation)
Mascot V has provided two sets of PWM, each PWM can generate programmable periodic
square waves; The generated wave consists of low period and high period, and the low period,
and the low period and high period can be programmed separately, each period basic cycles
that can be programmed to be 0 255 basic cycles; and the basic cycle is defined by design,
which also has four kinds of basic cycles can be chosen by programming.
Sync Processor
Sync Processor is used to detect input source (analog RGB or 24-bit RGB) and generate
interrupt to an external external CPU if input source changes. Then the CPU can program
Mascot V correctly according to different input sources. Sync Processor can generate
interrupt when there are frequency changes, Hsync and Vsync polarity changes, and when
there is no input signal. Sync processor provides h_counter and v_counter which are stored in
registers CR0B, CR0C, CR0D, and CR0E. V frequnecy can be calculated by (refclk/64) /
v_counter or 187.5kHz/ v_counter for using 12MHz refclk. H frequency is calculated by
(refclk/512k) * h_counter or 46.5Hz * h_counter or 46.5Hz * h_counter for using 12MHz refclk.
Mascot V Sync Processor can also support composite Sync and sync-on-green inputs. If sync
Processor detect that the input source is compusite sync or sync-on-green input, Mascot V
will separate composite sync or sync-on-green to Hsync and Vsync.
Calibration
Calibration block performs position calibration, color calibration and phase calibration. In
position calibration, non-zero data are detected horizontally and vertically. The Left most and
right most positions and their corresponding pitch can be found.Also Horizontal Total &
Vertical Total are calculated.
Color calibration includes maximum color component detection, color read back from
specified position and maximum color difference in 2 neighboring pixels.
ViewSonic Corporation
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