ViewSonic N4285p-4M, Service Manual

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1.13 DRAM Interface and Control
► Dual channel 16-bit DDR2 SDRAM interface (for uncompromised display quality)- Can support
Full HD features with only one piece of 16-bit DDR SDRAM
► Maximum DRAM speed is up to 800 MHz
► Maximum DRAM size is up to 1G bit per piece
► Programmable DRAM access timing and refresh timing
1.14 USB Host Controller with PHY
► Two USB ports with USB 2.0/1.1 compliance.
► Hardware accelerated JPEG decoding
► Hardware accelerated JPEG zooming and rotation
1.15 MISC
► Integrate 3 competitive EDID RAMs for HDMI_A (256 bytes), HDMI_B (256 bytes) and
VGA-DDC (128 bytes).
► High Speed SPI Interfaces to support single code flash and single data flash with content protection
► High Speed I2C with 400 KHz bus clock.
► Eight 5-level input IO for multi-level voltage sense.
► Hardware-accelerated IR with NEC, JVC, Sony SIRC, RC-5 and RC-6 compatibilities.
► Real Time Counter with Alarm function and Day-Light-Saving function.
► Up to 4 programmable PWM outputs
► UP to 64 General Purposed I/Os
► Support Dual UART
1.16 Process and Package Type
► 0.11um 3.3V/1.2V process
► 708-pin TEBGA package
4.2 GPIO Interface
The GPIO signals in SiS 328 are all multi-function pins. The default function is designated in each
pin definition, so is the input/output attribute. When in the output mode, assertion logic follows
the typical naming convention. For instance, BL_EN keeps low and becomes high when activated.
Alternating the default function to GPIO function involves register-programming. Input/output
mode or active level when in input mode, can then be redefined. Generally speaking, the GPIO
buffers in SiS 328 are categorized into two types. HSAGPIOxx employs type B which is a pure
3.3V buffer without an internal built-in pull-up or pull-down. Thus, an external pull-up to Standby
3.3V or pull-down is required to ensure that GPIO is not floated when it is configured in the input
mode.
The HVAGPIOxx category employs type C which is a 3.3V output and 5V input –tolerant with
internal pull-up when operated in the input mode. Note that the pull-up is
software-enabled/disabled. Upon power cord first plugged in, the pull-up is disabled.
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