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38 lines
1.5 KiB
Plaintext
38 lines
1.5 KiB
Plaintext
Pi is a Chinese device.
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We want port Openmoko to Pi, All free software
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1. open the case
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2. take off the cover of PCB
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then you will send the "GND" and "TXD"
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and th TP74 is the "RXD"
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you can get serial output from those pins
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3. you need a "RS-232 <--> TTL" converter to
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get the correct output date
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CPU Jz4740:
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Jz4740 is a multimedia application processor targeted at mobile devices
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PMP. Incorporates the XBurst CPU core based on leading
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micro-architecture technology, this processor provides high integration,
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high performance and a low power consumption solution for embedded devices.
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Boot up
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The Jz4740 can be set to boot from NOR or NAND.
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If booted from NAND, the CPU fetches the first page from NAND and uses the first 4 bytes on it to know how the NAND chip should be treated (16/8-bit bus, 2/3 row cycles).
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After that it copies the first 8kB from NAND and copies it to the I-Cache for execution.
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Ingenic Media Extension Instruction Set
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According to the MXU User Guide, the XBurst processor supports additional instructions called the Ingenic Media Extension Instruction Set (they call it an SIMD instruction set).
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Excerpt from the PDF:
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Processors (such as the Jz4740) have 60 extra SIMD commands used for the optimization of multimedia codecs such as MPEG4, H264, VC-1, RMVB, ... and other multimedia decoder algorithms that can be optimized using the MXU.
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Image Processing Unit
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The Jz4740 also has an IPU which has the following features:
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* Video frame resize
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* Color space conversion: 420/444/422 YUV to RGB convert
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