关于写C554的寄存器FCR的问题
诸如 LCR DLL DLH IER等寄存器,我都能写进去,再读出来,可FCR就是不行,
我把代码写在下面,哪位兄弟姐妹指导一下
//定义相关宏
#define UART_BASE_ADDR (0x20300000
#define C554_CH1_FCR (UART_BASE_ADDR+4)
#ifndef C554_REG_READ
#define C554_REG_READ(C554_reg, result) \
result = \
(*(volatile unsigned short *)(C554_reg)) #endif
#ifndef C554_REG_WRITE
#define C554_REG_WRITE(C554_reg, data) \
(*(volatile unsigned short *)(C554_reg)) = \
(data)
#endif
//写FCR寄存器
C554_REG_WRITE(C554_CH1_FCR, 0,0x1);// FCR0置1
C554_REG_WRITE(C554_CH1_FCR, 0,0x8f);// 向FCR寄存器写值
[解决办法]
FCR and ISR share the same address space in the UART regsiter set (0x02). The FCR is a write only register and the ISR is a read only register. When you do a write to address 0x02 you write to the FCR register, but when you do a read of address 0x02 you would read the ISR register and not the FCR register.
To overcome this problem you would have to save the FCR value to a variable before you write to the FCR register. And when you want to know what value is in the FCR register, you would read this value from the variable
