I/O系统，计算周期寄存器和一个预分频值
I/O Systems, calculate period register and a prescale value
问题是：
Consider a 16-bit timer that has seven prescaling options: 1:64, 1:32,
1:16, 1:8, 1:4, 1:2, 1:1. The timer is clocked at a frequency of 50
Mhz. Assume further that the timer is configured to trigger an
interrupt. Decide on a value for the period register and a prescale
value such that the interrupt is triggered every 20 ms.
我的答案是：周期寄存器值 125000 和预分频值 1:8
peruid 寄存器值是正确的，但他们说的预分频值：
"The period value does not fit in the period register".
这是什么意思，我怎么看？
来自你的引述：... a 16-bit timer ...
显然 16 位寄存器不能保存 125000 的值。
您至少需要 1:16
的预分频器
数学：
period * (freq / prescaler) = timer-value
您必须从可能的值中选择预分频器值，以便定时器值在 16 位范围内
问题是：
Consider a 16-bit timer that has seven prescaling options: 1:64, 1:32, 1:16, 1:8, 1:4, 1:2, 1:1. The timer is clocked at a frequency of 50 Mhz. Assume further that the timer is configured to trigger an interrupt. Decide on a value for the period register and a prescale value such that the interrupt is triggered every 20 ms.
我的答案是：周期寄存器值 125000 和预分频值 1:8
peruid 寄存器值是正确的，但他们说的预分频值：
"The period value does not fit in the period register".
这是什么意思，我怎么看？
来自你的引述：... a 16-bit timer ...
显然 16 位寄存器不能保存 125000 的值。
您至少需要 1:16
的预分频器数学：
period * (freq / prescaler) = timer-value
您必须从可能的值中选择预分频器值，以便定时器值在 16 位范围内