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因为玩uboot-2009.6风险实在太高,动手之前得准备好心脏起搏器以备不测,所以事先准备了 Wiggler-JTAG,ls2上焊了JTAG头。接法是这样:
LS2 CN9 --> Wiggler 20pin
1 --> 3 (nTRST)
3 --> 5 (TDI)
5 --> 13 (TDO)
7 --> 7 (TCK)
9 --> 9 (TMS)
2 --> 4 (GND)
14 --> 2 (VCC)
结果接上后openwince-jtag怎么都detect不到flash的信息,urJTAG报告说TDO始终为0。自己量了一下与Wiggler的Vcc相连的CN9的pin14竟然只有1.62v,于是把pin14接到板上串口的vcc,把电压拉高到3.3v,结果还是一样没戏。有玩过ls2-jtag的哥们给瞅一眼接的有啥问题没有,第一次玩JTAG,实在是没辙了。
BTW: 接法参考了下面这两组pinout定义
ls2上的14pin CN9 JTAG口定义
Signal Pin Notes
nTRST 1 must be pulled high if not controlled by the JTAG cable. Tie pin 14 to pin 1 with a 1K resistor.
TDI 3 -
TDO 5 Series Resistor R64 not installed - Installed 330 ohm resistor
TCK 9 -
TMS 7 -
Ground 2 -
Power 14 Series resistor R181 and decoupling capacitor C35 not installed. - Bridged R181, didn't install C35.
并口Wiggler-JTAG的20pin定义
Usual pin-out for 20-pin JTAG header (sometimes used forARM)
1 - Vddh (+3.3v)
2 - Vddh (+3.3v)
3 - nTRST
4 - Vss (ground)
5 - TDI
6 - Vss (ground)
7 - TMS
8 - Vss (ground)
9 - TCK
10 - Vss (ground)
11 - -------
12 - Vss (ground)
13 - TDO
14 - Vss (ground)
15 - nRST
16 - Vss (ground)
17 - --------
18 - Vss (ground)
19 - --------
20 - Vss (ground)
墙外的参考链接
http://sites.google.com/site/shi ... s/unbrick-with-jtag |
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