The zip file includes a Fritzing (http://www.fritzing.org/) picture on how to connect the chip. It should work also for other chips of the same family (X9Cxxx, xxx=102,103,104,503 according to datasheet).
Had a quick look at the code and it looks nice , still some remarks.
why not mapping the UP and DOWN as follows?
define DIGIPOT_UP HIGH (or 1)
define DIGIPOT_DOWN LOW (or 0)
would make change() a bit simpler
direction can be of type uint8_t, big enough to hold LOW/HIGH value.
pinnumbers in the constructor can be uint8_t (aka byte)
unsigned prevents negative numbers
and the range is big enough I guess
==> also the private vars to hold the pinnrs can be uint8_t
void increase(int amount);
as amount is a signed int it can accept negative numbers. Note that the for loop inside change() needs a positive amount.
Solution: Use an uint16_t for amount !
what is the max value of amount? you might consider using the constrain function ...
idem for decrease() and change() signatures..
Idea:
* It might be interesting to hold the cumulative value of all changes since start in a signed long. MIght be indicative for its value.
Can the value be read from the digipot?
Thanks a lot, Rob, for your comments. It's good to see that there's feedback available for newbies.
I uploaded an updated version of the library with datatype, direction handling and constrain() changes you suggested.
The ability to read back the changes I left for future development. I've also been thinking adding some reset() call, to reset the pot into a known state (like zero), and after that the library could hold the actual state of the potentiometer, and also set it to an absolute value. But, later maybe :)
v.4, updated on May 26, 2011: modified to be compatible with Arduino 1.0; added set() to set absolute potentiometer values.
typo on the website - hint it is the year
You might add a link in the header of the .cpp /.h file to this thread to discuss the functionality.
Did some refactoring to optimize the code as some checks were made double - just give it a look if you like it
also caught one bug in set() ==> if the _currentValue is unknown you may not do math with it I assume
void DigiPot::reset()
{
change(DIGIPOT_DOWN, DIGIPOT_MAX_AMOUNT); //_currentValue should in fact be enough...?
}
void DigiPot::set(uint8_t value)
{
value = constrain(value, 0, DIGIPOT_MAX_AMOUNT);
if (_currentValue == DIGIPOT_UNKNOWN)
change(DIGIPOT_DOWN, DIGIPOT_MAX_AMOUNT);
else if (_currentValue > value)
change(DIGIPOT_DOWN, _currentValue-value);
else if (_currentValue < value)
change(DIGIPOT_UP, value - _currentValue);
}
uint8_t DigiPot::get()
{
return _currentValue;
}
void DigiPot::increase(uint8_t amount)
{
change(DIGIPOT_UP, amount);
}
void DigiPot::decrease(uint8_t amount)
{
change(DIGIPOT_DOWN, amount);
}
Change() can be optimized by not allways doing amount steps automatically but check if _currentValue == 0 or max too. But it might make the code more complex.
