编译时出错：从'void *'到'unsigned char *'的无效转换

Question

我正在编程Arduino mega 2560。 我买了一台tft液晶显示器，为此我想使用SD卡，这样我就可以把它放在上面了。

我下载了这个库，但它给了我错误。

C:\Arduino\libraries\pff\pff.cpp: In function 'FRESULT pf_read(void*, short unsigned int, short unsigned int*)':
C:\Arduino\libraries\pff\pff.cpp:585: error: invalid conversion from 'void*' to 'unsigned char*'

问题在于：

pff.cpp：

 FRESULT pf_read (
    void* buff,     /* Pointer to the read buffer (NULL:Forward data to the stream)*/
    WORD btr,       /* Number of bytes to read */
    WORD* br        /* Pointer to number of bytes read */
)

pff.h：

FRESULT pf_read (void*, WORD, WORD*);           /* Read data from the open file */

当我把它变成.c文件时，它会给我更多错误，比如这个错误：

tft_menu.cpp.o: In function `open_root_dir()':
C:\AppData\Local\Temp\build7310099894910129341.tmp/tft_menu.cpp:594: undefined reference to `pf_opendir(_DIR_*, char const*)'
tft_menu.cpp.o: In function `mount_sd()':
C:\AppData\Local\Temp\build7310099894910129341.tmp/tft_menu.cpp:583: undefined reference to `disk_initialize()'
C:\AppData\Local\Temp\build7310099894910129341.tmp/tft_menu.cpp:585: undefined reference to `pf_mount(_FATFS_*)'
tft_menu.cpp.o: In function `bitmap_show(char*)':
C:\AppData\Local\Temp\build7310099894910129341.tmp/tft_menu.cpp:472: undefined reference to `pf_open(char const*)'
C:\AppData\Local\Temp\build7310099894910129341.tmp/tft_menu.cpp:476: undefined reference to `pf_read(void*, unsigned short, unsigned short*)'
C:\AppData\Local\Temp\build7310099894910129341.tmp/tft_menu.cpp:518: undefined reference to `pf_read(void*, unsigned short, unsigned short*)'
tft_menu.cpp.o: In function `show_bitmap()':
C:\AppData\Local\Temp\build7310099894910129341.tmp/tft_menu.cpp:603: undefined reference to `pf_readdir(_DIR_*, _FILINFO_*)'

所以我认为它应该编译为cpp。

编辑：

我发现我必须保存为cpp，在程序中我必须写出icktoofay状态

之后我遇到了一些错误，所以我按照上面的说明进入了第585行并更改了

BYTE * rbuff = buff;

进入

BYTE rbuff =（unsigned char ）buff;

我发现我必须添加mcc.h来摆脱“无法找到资源”的错误。

现在我得到了这些错误：

C:\libraries\mmc/mmc.h: In function 'void init_spi()':
C:\libraries\mmc/mmc.h:21: error: 'PORTL' was not declared in this scope
C:\libraries\mmc/mmc.h:21: error: 'PORTL0' was not declared in this scope
C:\libraries\mmc/mmc.h:22: error: 'PORTB' was not declared in this scope
C:\libraries\mmc/mmc.h:22: error: 'PORTB2' was not declared in this scope
C:\libraries\mmc/mmc.h:22: error: 'PORTB1' was not declared in this scope
C:\libraries\mmc/mmc.h:23: error: 'DDRB' was not declared in this scope
C:\libraries\mmc/mmc.h:23: error: 'PORTB0' was not declared in this scope
C:\libraries\mmc/mmc.h:25: error: 'DDRL' was not declared in this scope
C:\libraries\mmc/mmc.h:27: error: 'SPCR' was not declared in this scope
C:\libraries\mmc/mmc.h:27: error: 'SPE' was not declared in this scope
C:\libraries\mmc/mmc.h:27: error: 'MSTR' was not declared in this scope
C:\libraries\mmc/mmc.h:28: error: 'SPSR' was not declared in this scope
C:\libraries\mmc/mmc.h:28: error: 'SPI2X' was not declared in this scope

我试过在mcc.h上添加#include TFT_ARDUINO_MEGA.h并且仍然没有运气

Answer 1

将其编译为C文件，但在使用它的文件中，包括pff.h，如下所示：

extern "C" {
#include <pff.h>
}