Sample Implementation of Revised PinMode Definition For KL25Z

[bridadan]

DO NOT MERGE

The rest of the platforms will have to be updated too before this could be merged.

This is a sample implementation for the KL25Z of the changes I proposed in this issue: #1064

I've made a few changes. I've moved the mentioned function gpio_mode_supported in the issue to the pinmap api as int pin_supports_mode(PinName pin, PinMode mode);. You can also configure an input pin to an unsupported mode, as all possible PinModes are now defined for all platforms. Right now it will simply ignore the request and leave the pin unchanged. However, you can proactively check if the pin supports a given PinMode by calling pin_supports_mode.

I've tested this with the KL25Z using the automated test suite and it passes all tests. I've also used a logic analyzer and I can see the "PullUp" and "PullNone" options changing the idle level of the pin.

I'd like to hear feedback on this change. How could this be better organized? Should the C++ API be changed as well to return information on (un)supported PinModes?

[bridadan]

Trying to start some discussions on this. Does this seem like a worthwhile change? Do we need to add a broader mechanism so mbed platforms can discover what they are capable of at runtime, not just for PinModes? I think this would help with writing libraries to be more general and cross platform.

[sg-]

A few comments on the PR and then I think @bridadan can make the changes for all existing platforms.

1. leaving PinMode in each platform but making a requirement to use the same elements, just modify the values per device.

typedef enum {
    Unsupported = -1,
    PullNone = 1,
    PullUp = 2,
    PullDown = Unsupported,
    OpenDrain = 3,
    Repeater = Unsupported,
    PullDefault = PullNone,
} PinMode;

You could then just test by (mode != Unsupported) and etc...

[0xc0170]

@bridadan I am closing this as it has been some time. You can turn it into an issue where we can continue the discussion.

[bridadan]

@0xc0170 Makes sense to me 👍