Add Dip Switch as a core feature

[drashna]

Description

This pulls out the dip switch code from the Planck Rev 6 and the Preonic Rev 3 code, and removes the need for a custom matrix. This includes defining pins for them.

And it generalizes the code, so that anyone can just drop in the settings (as long as they're correct), and use the feature.

Credit goes to @jackhumbert for the original code. Though, I did do some optimization of it, to make it more compact and expandable. And thanks to /u/VegetableStu on reddit for the inspiration for this.

I've tested with the Planck Rev6 and can confirm that it has the correct functionality. However, I don't have a Preonic Rev3 to test the changes on (but they should be the same as the planck)

Types of Changes

• Core
• New feature
• Keyboard (addition or update)
• Documentation

Issues Fixed or Closed by This PR

• https://www.reddit.com/r/olkb/comments/c0uf84/qmk_help_topmost_layer_always_being_default_layer/

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[mtei]

I think you can remove NUMBER_OF_DIP_SWITCHES from config.h.

diff --git a/quantum/dip_switch.c b/quantum/dip_switch.c
index cb6c1e231..c69111c31 100644
--- a/quantum/dip_switch.c
+++ b/quantum/dip_switch.c
@@ -21,16 +21,13 @@
 // for memcpy
 #include <string.h>
 
-
-#ifndef NUMBER_OF_DIP_SWITCHES
-#   error "Number of DIP switches not defined by NUMBER_OF_DIP_SWITCHES"
-#endif
-
 #if !defined(DIP_SWITCH_PINS)
 #   error "No DIP switch pads defined by DIP_SWITCH_PINS"
 #endif
 
-static pin_t dip_switch_pad[NUMBER_OF_DIP_SWITCHES] = DIP_SWITCH_PINS;
+#define NUMBER_OF_DIP_SWITCHES (sizeof(dip_switch_pad)/sizeof(pin_t))
+
+static pin_t dip_switch_pad[] = DIP_SWITCH_PINS;
 static bool dip_switch_state[NUMBER_OF_DIP_SWITCHES] = { 0 };
 static bool last_dip_switch_state[NUMBER_OF_DIP_SWITCHES] = { 0 };

[drashna]

@mtei I wasn't sure if that would actually work, but yup, it does!!

[mtei]

I think that it is good to update show_options.mk. :-)

[tuzonghua]

@drashna I tested this on a non-planck/preonic board and it worked great! Just adding the dip_switch_update_user call in my keymap.c allowed me to set certain layers as active etc. However, the current implementation (I believe) only allows for as many options as there are DIP switches on the board (so 4 for Preonic).

It might be worth expanding the implementation so that n^2 options are available to set. This would, for example, allow for setting 4 different layouts using just the first 2 switches (00, 01, 10, 11), which is what some WASD boards do (see here).

[noroadsleft]

I quite like @tuzonghua's suggestion, but IMO we can get this into core and then enhance the feature later.

[zvecr]

@noroadsleft While i agree with the incremental approach, changing the API at a later date only adds complications. API deprecation would have to eventually lean on the breaking change process.

For instance, using a single uint8_t, instead of an array of 6 bools is more efficient.
A typedef to switch between 8,16,32, as per pin_t used for matrix.
Add some bit masking and a change to the api so its called once on change, called with the current state.

[tuzonghua]

@drashna If there's a way to achieve my suggestion without rewriting a bunch of the existing code in this PR, may you please add an extra example to the docs? At least until the next iteration can be implemented.

[drashna]

Thanks for the suggestion. I've actually implemented this, and it was pretty simple to do so.

In fact, it actually implements both methods, at the same time. So if you want the dead simple version, don't use the mask callbacks. But if you want more complex, that's an option, too!

Also, this led to discovery of a bug in the config for the planck rev6 and preonic rev3 dip switch configuration (wrong pin was used). So that's fixed as well.

Either way, I think this should now be super useful to anyone that wants to use it, no matter how they want to use it.

[tuzonghua]

Thanks for the improvements! However, the bit mask still doesn't quite work as expected. I created three test layers, placing a different letter on the ESC key and the two cases where only one switch is on worked, but the case where both switches are on didn't. Here's that example:

void dip_switch_update_mask_user(uint32_t state) {
  if (state & (1UL<<0) && state & (1UL<<1)) {
    layer_on(_ADJUST); // C on esc
  } else {
    layer_off(_ADJUST);
  }
  if (state & (1UL<<0)) {
    layer_on(_TEST_A); // A on ESC
  } else {
    layer_off(_TEST_A);
  }
  if (state & (1UL<<1)) {
    layer_on(_TEST_B); // B on esc
  } else {
    layer_off(_TEST_B);
  }
}