In AVR programming with atmega32, I can't assign a value to an array. I am getting the error:

> 
> Assignment of read-only str[i]
> 
> 
> 

What am I doing wrong?

My code is:

```
const char str[1000];
void Serial_tx(unsigned char ch)
{
  for (i = 0; i < 10; i++)
  {
    str[i] = ch;
  }
}

```