1.时钟电路
TMS320VC5509A的内部振荡器复位时为有效。内部振荡器需要外部晶体支持,连接到X1和X2/CLKIN引脚。如果不用内部振荡器,外部时钟连接到X2/CLKIN引脚,X1引脚悬空。当内部振荡器作为时钟源输入到PLLs时,振荡器时钟可以倍频或分频成为CPU时钟、USB时钟等。
电路连接图如下图所示:
各电阻电容值参考下表:
1.PPLs
(1)Clock Generation in Bypass Mode (DPLL Disabled)
通过时钟模式设置寄存器的BYPASS_DIV位可以设置DPLL失效。
(2)Clock Generation in Lock Mode (DPLL Synthesis Enabled)
The frequency of the reference clock provided at the X2/CLKIN pin can be multiplied by a synthesis factor of N to generate the internal CPU clock cycle. The synthesis factor is determined by:
N=M/D
where: M = the multiply factor set in the PLL_MULT field of the clock mode register
D = the divide factor set in the PLL_DIV field of the clock mode register
Valid values for M are (multiply by) 2 to 31. Valid values for DL are (divide by) 1, 2, 3, and 4.
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