DSP tms28377 DAC

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DSP tms28377 DAC [复制链接]

DSP tms28377 DAC

有三个dac,,对应的寄存器为:
extern volatile struct DAC_REGS DacaRegs;
extern volatile struct DAC_REGS DacbRegs;
extern volatile struct DAC_REGS DaccRegs;

Using the DAC
The reference voltages for the internal DAC are selectable between the two voltage pairs:
• VDAC and VSSA
• VREFHI and VREFLO

Two sets of DACVAL registers are present in the buffered DAC module: DACVALA and DACVALS.
DACVALA is a read-only register that actively controls the DAC value. DACVALS is a writable shadow
register that loads into DACVALA either immediately or synchronized with the next PWMSYNC event.
The ideal output of the internal DAC can be calculated as follows:
Vdac = ( DACVALA * DACREF )/ 2^12;
++影子寄存器的引入是ARM的一个特点（X86，PowerPC都没有）。我们知道，ARM有16个通用寄存器，这16个通用寄存器在指令中使用4个bit识，但是在不同的模式下，同样的4个bit 指向不同的物理寄存器，这些不同的物理寄存器就被称之为影子寄存器。不同的通用寄存器的影子寄存器个数也不相同，有的没有，有的只有1个，有的多达5个。要记住一点：所有的影子寄存器都是一个实际存在的物理寄存器