1. Mx6u startup mode and equipment

Starting mode ：. modify GPIO level

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principle ：

By modifying the BOOT_MODE[1:0] High and low level selection 4 Clocks correspond in different ways

type ：

  Serial download ：

principle ： adopt USB perhaps UART Download the code to the external storage device on the board

Inside BOOT Pattern ：

principle ： The chip runs internally boot ROM, then boot ROM Will perform hardware initialization , And then from boot equipment （SD card ） Copy the code to the specified RAM（DDR）

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In the internal BOOT Based on the model , Start the equipment

principle ： adopt BOOT_CFG1[7:0],BOOT_CFG2[7:0],BOOT_CFG4[7:0], this 24IO Port configuration , this 24 to IO Mouth and BOOT_MODE[0:1] Constitutes the start selection pin .

characteristic ：

Upper section IO Ports do not need to be configured , for example BOOT_CFG4[7:0] Grounded . Just for the rest 16 individual IO Port configuration , And the dial switch of the board LCD DATAX And above IO The oral relationship is as follows

Dial mode ：

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  summary ：

From the inside IO The working mode of the interface is mapped to the dial switch on the upper layer to determine the starting mode of the board , Select the dial switch according to different needs .