TM4C123GH6PM DATASHET 715页
Each time a rising edge event is detected, the current count value is loaded into the GPTMTnR and
GPTMTnPS registers, and is held there until another rising edge is detected (at which point the new
count value is loaded into the GPTMTnR and GPTMTnPS registers).
想要读取寄存器GPTMTnR和GPTMTnPS的值进行运算处理，但是TIVAWARE中没找到读取的函数，也找不到寄存器地址，求助外设寄存器的地址或者读取函数。。。
