pinMode1 - Silent failure using 0 vs using OUTPUT.

[Spaceballs3000]

Unless you check the return value, I didn't know pinMode1 was failing using 0 vs using OUTPUT. As 0 is invalid.

Noticed OUTPUT is defined as 0x03.

Also the function description is Incorrect i.e. "single pin interface mode: 0 = OUTPUT, 1 = INPUT, 1 = INPUT_PULLUP (==INPUT)"

[RobTillaart]

From Datasheet REV_D

Quick test Arduino UNO constants

Serial.println(OUTPUT);
Serial.println(INPUT);
Serial.println(INPUT_PULLUP);

results in

1
0
2

So OUTPUT == 1 and INPUT == 0, ==> incorrect documentation.

Code

relevant piece of MCP23S17.cpp (about line 134)

  uint8_t mask = 1 << pin;
  //  only work with valid
  if ((mode == INPUT) || (mode == INPUT_PULLUP))
  {
    val |= mask;  <<<<<<<<  sets bit as a 1
  }
  else if (mode == OUTPUT)
  {
    val &= ~mask;   <<<<<<<<<  sets bit to 0
  }
  //  other values won't change val ....
  writeReg(dataDirectionRegister, val);

Conclusion

So the device behaves as expected when using the constants / defines INPUT and OUTPUT
but not when using 0 or 1.

Serious documentation error ==> bug level.

Will create a develop branch to start a fix.

Note to myself: check examples + MCP23008, MCP23017, MCP23S08 libraries too.

[RobTillaart]

@Spaceballs3000

Noticed OUTPUT is defined as 0x03.

Which platform do you use?

[RobTillaart]

Note to myself: check examples + MCP23008, MCP23017, MCP23S08 libraries too.

Other 3 libraries have the same documentation bug, => create issues.

[RobTillaart]

Note: bug comes from using the bit mask where 0 means output mode and 1 means input mode.

[RobTillaart]

Will update the readme.md file to

• bool pinMode1(uint8_t pin, uint8_t mode) pin = 0..15, mode = INPUT, OUTPUT or INPUT_PULLUP.
  Do NOT use 0, 1 for mode as the 3 constants are (possibly) defined differently.
  Returns true if successful.

In the .h file some similar comment.

[RobTillaart]

@Spaceballs3000
Created develop branch for version 0.5.4 with updated documentation.

[Spaceballs3000]

@Spaceballs3000

Noticed OUTPUT is defined as 0x03.

Which platform do you use?

In my case the define came from esp32-hal-gpio.h

[RobTillaart]

@Spaceballs3000
All four repo's have updated readme.md and updated comments in .h / .cpp.
It should disambiguate the use of parameters for pinMode1()

Will merge develop branch(es) later today,

(update) did not find problems in the examples.