页数               内容

1-15               通过JTAG调试板子,通过串口或USB引导加载操作系统


Table 3-7.   AIPI1 Memory Map

0x1000 A000 – 0x1000 AFFF             UART1       4 Kbyte

0x1002 4000 – 0x1002 4FFF              USB OTG     4 Kbyte

0x1002 5000 – 0x1002 5FFF              USB OTG     4 Kbyte


Table 7-20.   Reset Module Pin and Signal Descriptions

HRESETHard Reset—An active low signal that resets the ARM9 Platform. This signal is deasserted during the low phase of HCLK. This signal also appears on the RESET_OUT pin of the i.MX21.


7.4.2   ARM9 Platform Reset

Any qualified global reset signal resets the ARM9 platform and all related peripherals to their default state. After the internal reset is deasserted, the ARM9 processor begins fetching code from the internal bootstrap ROM or CS0 space. The memory location of the fetch depends on the configuration of the BOOT pins and the value of the TEST pin on the rising edge of the HRESET.


7-32 系统从片选信号CS0对应存储区域或者是从iROM启动,这取决于BOOT[3:0]的设置和处于HRESET上升沿时TEST pin的值。


9.2   System Boot Mode Selection

If the fuse of the BOOT_INT is blown(表9-2Blown = Internal=1?), the BOOT Address will be generated based on the BOOT[3:0] information.


Silicon ID RegisterBOOT_INT=0时,从由BOOT[3:0]所决定的外部存储空间启动;

Silicon ID RegisterBOOT_INT=1时,从0x0处启动。


The BOOT pins must not change once the i.MX21 is out of reset. For proper operation, BOOT[3] must always be tied to VSS.


BOOT[3:0]决定了映射到0x0的外部存储地址,即Reset Vector的值。

处理器启动顺序由SIDRBOOT[3:0]的配置决定,默认BOOT_INT=0时,即从由BOOT[3:0]所决定的外部存储空间启动。           Wafer Test

By default, the silicon is configured to bootup externally and all security related modules are disabled via the default laser fuse setting (unblown state).

Power-on-reset (POR)


Development Part:

It first reads the Laser-fuse HAB_TYPE as 0001 to confirm it is a Development Part and BOOT[3:0] is 0000, indicating USB/UART bootstrap.


Chapter 11     Bootstrap Mode Operation

The bootstrap program is a small program which resides in the internal ROM of i.MX21.


1. For HAB Enable type of silicon, it downloads authenticated binary image code to memory so as to execute in run time or perform Flash update.

2. For HAB Disable type of silicon, it downloads binary image code to memory as to execute in run time or perform Flash update.



The Configuration for USB is for Control Endpoint 0 with Max Packet Size equal 8 byte. Bulk IN at Endpoint 2 with Max Packet Size equal 64 bytes, Bulk OUT at Endpoint 1 with Max Packet Size equal 64 bytes.


Table 21-1.   RTIC Signal Descriptions

Hreset Master Hardware Reset—Active-low asynchronous hardware reset. This signal must always be asserted with HARD_ASYNC_RESET.

posted on 2008-09-03 22:48 milkyway 阅读(897) 评论(0)  编辑 收藏 引用 所属分类: 基础知识

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