32 lines
1.1 KiB
Markdown
32 lines
1.1 KiB
Markdown
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简介：
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本工程主要演示psram的初始化以及读写操作
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注意事项：
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psram进行读写操作软件应用层面需要做原子保护
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###Brief:
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This example shows how to
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* init psram: call psram_enable() API
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* PSRAM_CACHE_F40M_S40M mean flash cache 40Mhz and sram cache 40Mhz, which is the recommended option in current version.
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* read & write psram: Must add lock for read/write operations in this version.
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* We need to initialize mmu in set_cache_and_start_app() of bootloader_start.c, refer to bootloader_start.c in the demo folder.
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```
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//32KBytes for each page, totally 128 pages, that is 4MBytes.
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cache_sram_mmu_set( 0, 0, 0x3f800000, 0, 32, 128 );
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```
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###Restrictions:
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1. GPIO16, GPIO17 and GPIO20 are occupied, can not be used in app code.
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2. GPIO matrix signal 224 and 225 are occupied, can not be used in app code.
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3. SPI1 is used to initialize the psram chip.
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4. Must add lock for psram read/write operations in this version.
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5. ~~For now, we have some confilcts between spi flash read/write and psram driver, we will resolve it soon.~~
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###update on 161206: Item No.5 has been fixed
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