[ARM] "unsigned char" is always true ....?

bianchi77 said:

What should I change for fixing :
Warning : comparison of constant 49152 with expression of type "unsigned char" is always true ....?

Click to expand...

Mp3ReadRegister(0x03) != CLOCK_REG

bigdogguru said:

The simple fact is the following conditional is always true:

Code:

Mp3ReadRegister(0x03) != CLOCK_REG

How can a type of unsigned char with a maximum value of 0xFF, ever equal 0xC000?

It obviously cannot.

The only way the above conditional makes sense is if your defined value of CLOCK_REG is within the range of an unsigned char, 0x00 to 0xFF.


BigDog

Click to expand...

FvM said:

O.K., but what's inside the function body? How's the return value derived? Is it a 16-bit register read result? With an ANSI C compiler, a 16-bit value would have the type unsigned, not unsigned long.

I don't understand why you have changed the address type, too.

Click to expand...

unsigned long Mp3ReadRegister( unsigned long addressbyte)
{
	

	int resultvalue = 0;
	Mp3DeselectData();
	Mp3SelectControl();				//XCS = 0
	uint8_t data7[2] = { VS_READ_COMMAND, addressbyte };
	
	HAL_SPI_Transmit(&hspi1,data7,2,1000);
	uint8_t data8[1] = {0x00};
  data8[0] = 0;
	
	
	
	HAL_SPI_Receive(&hspi1,data8,1,1000);
	resultvalue = data8[0];
	resultvalue <<= 8;
	HAL_SPI_Receive(&hspi1,data8,1,1000);
	resultvalue += data8[0];
   	
	Mp3DeselectControl();              
	return resultvalue;           	//??16??????

}