IMX6Q设置启动模式

1. UBOOT查看目前BT_CFG1、BT_CFG2、BT_CFG3、BT_CFG4管脚设置

U-Boot 2015.04-svn3 (Jan 22 2016 - 15:02:38)

CPU:   Freescale i.MX6Q rev1.2 at 792 MHz
CPU:   Temperature 42 C
Reset cause: POR
Board: MYZR i.MX6 Evaluation Kit
Model: MY-IMX6-EK200-6Q-1G
I2C:   ready
DRAM:  1 GiB
MMC:   FSL_SDHC: 0, FSL_SDHC: 1
SF: Detected SST25VF016B with page size 256 Bytes, erase size 4 KiB, total 2 MiB
*** Warning - bad CRC, using default environment

No panel detected: default to Hannstar-XGA
Display: Hannstar-XGA (1024x600)
In:    serial
Out:   serial
Err:   serial
Net:   Phy 0 not found
FEC [PRIME]
Normal Boot
Hit any key to stop autoboot:  0 
=> 
=> md 020d8004

020d8504: 18000030 00000000 00000000 00000000    0...............
020d8514: 00000000 0000001f 22000011 00000000    ..........."....
020d8524: 00000000 00000000 00000000 00000000    ................
020d8534: 00000000 00000000 00000000 00000000    ................
020d8544: 00000000 00000000 00000000 00000000    ................
020d8554: 00000000 00000000 00000000 00000000    ................
020d8564: 00000000 00000000 00000000 00000000    ................
020d8574: 00000000 00000000 00000000 00000000    ................
020d8584: 00000000 00000000 00000000 00000000    ................
020d8594: 00000000 00000000 00000000 00000000    ................
020d85a4: 00000000 00000000 00000000 00000000    ................
020d85b4: 00000000 00000000 00000000 00000000    ................
020d85c4: 00000000 00000000 00000000 00000000    ................
020d85d4: 00000000 00000000 00000000 00000000    ................
020d85e4: 00000000 00000000 00000000 00000000    ................
020d85f4: 00000000 00000000 00000000 00000520    ............ ...

其中 18000030  代表：

              

       BOOT_CFG2[7:0]         BOOT_CFG1[7:0]

               00                                30  

对照下表：

发现当前是从spi启动的。

2. SABRE-SD 进入Serial Download Mode

1.No dedicated boot dips are reserved for serial download mode on SABRE-SD board. Therefore, a tricky method is used
to enter serial download mode. Change the SABRE-SD SW6 (boot) to 00001100 (from 1-8 bit) to enter download
mode.
2. Power on the board. Using the USB cable on the SABRE-SD OTG port, connect a computer running the Windows OS
to the SABRE-SD board