之前一直用winavr作为avr开发工具,AVRstudio 5以后的版本直接包含了GCCAVR工具链,开发环境也变化比较大,总体还是非常给力的,所以一直跟着版本更新,原来的程序直接拷贝编译无法通过,出现最多的是这个错误:
错误 __builtin_avr_delay_cycles expects an integer constant.
经过查找发现是头文件版本更新所致。delay.h文件214行说明如下:
Note: The new implementation of _delay_us(double __us) with
__builtin_avr_delay_cycles(unsigned long) support is not backward compatible.
User can define __DELAY_BACKWARD_COMPATIBLE__ to get a backward compatible delay.
Also, the backward compatible
algorithm will be chosen if the code is compiled in a <em>freestanding
environment</em> (GCC option \c -ffreestanding), as the math functions
required for rounding are not available to the compiler then.
这样解决方法就明显了,新的定义和之前的不兼容,因此调用头文件之前加入define __DELAY_BACKWARD_COMPATIBLE__ 即可。
最后还是得感慨下AVR已经落伍了,没啥优势了,以后的项目8位的AVR不用考虑了,仿真器还那么贵,唉。