最近使用LPC4357芯片,用了很久都没有问题,今天突然用KEIL找不到目标板了,JTAG Device Chain中显示为空,同时我用J-flash软件也提示AUTO detection of CPU clock frequency is not supported for this core,不知道为什么,哪位大侠能解答下,万分感谢;
FR5739并不像g2553可以内部配置电容,所以在接外部晶振时要外接电容才可以起振:(a) For XT1DRIVE = {0}, C L,ef f ≤ 6 pF.(b) For XT1DRIVE = {1}, 6 pF ≤ C L,ef f ≤ 9 pF.(c) For XT1DRIVE = {2}, 6 pF ≤ C L,ef f ≤ 10 pF.(d) For XT1DRIVE = {3}