1.连线
参考wiki
| SD卡引脚 | JTAG引脚 | SD卡信号 |
| 8 | GND | GND |
| 1 | TCK | D2 |
| 8 | TMS | D1 |
| 7 | TDI | D0 |
| 3 | TDO | CMD |
| 4 | VT | VCC |
2.在windows将jlink固件升级为4.90a
较低的版本无法支持cortex-a7，至少这个版本是支持的。需要一提的是，在windows系统，jlink无法识别 cortex-a7。这一步只是避免在ubuntu系统中
再次升级。方法略。
3.在ubuntu安装和windows相同版本的jlink软件
在ubuntu系统（我用到是12.04）中，对应的版本是4.90.1，只所以安装和windows相同的版本，是为了避免在linux升级jlink固件，因为在linux升级固件
会导致jlink损坏。
然或输入 JLinkExe，显示：
Feature(s): RDI,FlashDL,FlashBP,JFlash,GDBFULL
VTarget = 3.280V
Info: TotalIRLen = 4, IRPrint = 0x01
Info: ARM AP[0]: 0x64770001, AHB-AP
Info: ARM AP[1]: 0x44770002, APB-AP
Info: Found Cortex-A7 r0p4
Info: 6 code breakpoints, 4 data breakpoints
Info: Debug architecture ARMv7.1
Info: Data endian: little
Info: Main ID register: 0x410FC074
Info: L1 (I-cache): 32 KB, 512 sets, LineSize 32 bytes, 2-way
Info: L1 (D-cache): 32 KB, 128 sets, LineSize 64 bytes, 4-way
Info: L2 (unified cache): 256 KB, 512 sets, LineSize 64 bytes, 8-way
Info: System control register:
Info: Instruction endian: little
Info: Level-1 instruction cache disabled
Info: Level-1 data cache disabled
Info: MMU disabled
Info: Branch prediction enabled
Found 1 JTAG device, Total IRLen = 4:
#0 Id: 0x5BA00477, IRLen: 04, IRPrint: 0x1, CoreSight JTAG-DP (ARM)
Cortex-A7 identified.
Target interface speed: 100 kHz