新焊了一块V3s板子,24Mhz起振, 几组电源都正常，但是电脑不能识别usb设备，也不能从烧好的flash启动,这是什么原因?
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板子设计没有问题，已经有一片好的?
一共做了10片板子， 贴了三片， 两片正常， 这一片就是有问题， 怎么都没找到问题.
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把JLINK接上去了,
SEGGER J-Link Commander V4.96l ('?' for help)
Compiled Feb 25 2015 10:24:24
DLL version V4.96l, compiled Feb 25 2015 10:24:11
Firmware: J-Link V9 compiled Dec 1 2017 14:40:21
Hardware: V9.40
S/N: 59402905
Feature(s): RDI, GDB, FlashDL, FlashBP, JFlash
VTarget = 3.340V
Info: TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
Info: TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
No devices found on JTAG chain. Trying to find device on SWD.
Info: TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
Info: TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
No device found on SWD.
Trying to find device on FINE interface.
Info: TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
Info: TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
No device found on FINE interface.
Did not find any core.
Failed to identify target. Trying again with slow (4 kHz) speed.
Info: TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
Info: TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
No devices found on JTAG chain. Trying to find device on SWD.**************************
WARNING: RESET (pin 15) high, but should be low. Please check target hardware.
****************************************************
WARNING: RESET (pin 15) high, but should be low. Please check target hardware.
**************************No device found on SWD.
Trying to find device on FINE interface.
No device found on FINE interface.
Did not find any core.
No device found at all. Selecting JTAG as default target interface.
J-Link>
看起来都没找到内核
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V3s芯片肚子上的地线有没有焊，
或者再把芯片引脚再拖焊一下。
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这个最后找到原因了么？？
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这个最后找到原因了么？？
找到原因了，
109pin VCC-USB 电阻假焊了，
应该给3V3供电的。
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