Compiler/LAUNCHXL-CC2640R2: Porting Library for Temperature and Humidity Sensor

Andrew Ricci

Intellectual 290 points

Part Number: LAUNCHXL-CC2640R2

Tool/software: TI C/C++ Compiler

Hello, I'm working over the LAUNCHXL-CC2640R2, using the SHT31 sensor.

This the code:

These the output errors:

my experience on C/C++ is few, so these errors may be easy to correct but I'm just wondering around, any help is deeply appreciated

Working with CCSv 7.4, and Compiler 16.9.6

Thanks!

over 7 years ago

0 Keith Barkley over 7 years ago

Guru 41995 points

Please post the code with the code facility here so I can copy and paste!

you make POLYNOMIAL a constant, but do not provide any initialization values.
What do you think uint8_t *crc(0xff) does?

Arrays use [], not ().
And later you treat crc as a straight variable, not a pointer.

You really need to learn C first.

0 George Mock over 7 years ago

TI__Guru**** 244710 points

I'll comment on two of the lines. I suspect fixing these will cause most of the remaining problems to go away.

Regarding ...

   const uint8_t POLYNOMIAL(0x31);

Initializing a local variable like that is not valid in C. But it is valid in C++. To make it work in C, write it ...

   const uint8_t POLYNOMIAL = 0x31;

Or, if you have a lot of this thing already, consider changing the file extension for the source file from .c to .cpp. This is the typical way to tell the compiler the source is C++, and not C.

Regarding ...

   uint8_t *crc(0xFF);

As for the initialization to 0xFF, it has the same problem as the previous example. But there is an additional problem. Note the * character. This says this is a pointer variable. Given the context, you don't want this variable to be a pointer, but a value. Remove the *.

Thanks and regards,

-George

0 Andrew Ricci over 7 years ago in reply to George Mock

Intellectual 290 points

Thank you very much for your answer.

Code with the proposed fixes and I corrected others as well... final code looks like this:

uint8_t crc8(const uint8_t *data, int len)
{
  const uint8_t POLYNOMIAL = 0x31;
  uint8_t crc = 0xFF;
  unsigned int j = 0;
  unsigned int i = 0;

  for (j = len; j; --j ) {
      crc ^= *data++;

      for (i = 8; i; --i ) {
          crc = ( crc & 0x80 )
                  ? (crc << 1) ^ POLYNOMIAL
                  : (crc << 1);
      }
  }
  return crc;
}

(Post it in the case would be useful for someone else...)

0 Andrew Ricci over 7 years ago in reply to George Mock

Intellectual 290 points

I solved the previous Issue, will post a new question for the other errors. thanks

0 Keith Barkley over 7 years ago in reply to Andrew Ricci

Guru 41995 points

What error do you get, the basic syntax is OK.

It is possible that the pointer to the array 'rxbuffer[]' is not compatible to a pointer to uint8_t.

try:

if (if (rxBuffer[2] != crc8(&rxBuffer[0], 2)) i=20;

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Compiler/LAUNCHXL-CC2640R2: Porting Library for Temperature and Humidity Sensor