Initial potentiometer support

quantum/keyboard.c

@@ -60,6 +60,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #ifdef ENCODER_ENABLE
 #    include "encoder.h"
 #endif
+#ifdef POTENTIOMETER_ENABLE
+#    include "potentiometer.h"
+#endif
 #ifdef HAPTIC_ENABLE
 #    include "haptic.h"
 #endif
@@ -143,6 +146,9 @@ uint32_t        last_input_activity_time(void) {
 uint32_t last_input_activity_elapsed(void) {
     return sync_timer_elapsed32(last_input_modification_time);
 }
+void last_input_activity_trigger(void) {
+    last_input_modification_time = sync_timer_read32();
+}
 
 static uint32_t last_matrix_modification_time = 0;
 uint32_t        last_matrix_activity_time(void) {
@@ -440,6 +446,9 @@ void keyboard_init(void) {
 #ifdef DIP_SWITCH_ENABLE
     dip_switch_init();
 #endif
+#ifdef POTENTIOMETER_ENABLE
+    potentiometer_init();
+#endif
 #ifdef SLEEP_LED_ENABLE
     sleep_led_init();
 #endif
@@ -669,6 +678,13 @@ void keyboard_task(void) {
     }
 #endif
 
+#ifdef POTENTIOMETER_ENABLE
+    if (potentiometer_task()) {
+        last_input_activity_trigger();
+        activity_has_occurred = true;
+    }
+#endif
+
 #ifdef POINTING_DEVICE_ENABLE
     if (pointing_device_task()) {
         last_pointing_device_activity_trigger();

quantum/potentiometer.c

@@ -0,0 +1,113 @@
+// Copyright 2023 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include "potentiometer.h"
+#include "gpio.h"
+#include "util.h"
+#include "timer.h"
+#include "analog.h"
+
+#ifndef POTENTIOMETER_THROTTLE_MS
+#    define POTENTIOMETER_THROTTLE_MS 1
+#endif
+
+#ifndef POTENTIOMETER_OUTPUT_MIN_VALUE
+#    define POTENTIOMETER_OUTPUT_MIN_VALUE 0
+#endif
+#ifndef POTENTIOMETER_OUTPUT_MAX_VALUE
+#    define POTENTIOMETER_OUTPUT_MAX_VALUE 127
+#endif
+
+////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// ADC Driver
+
+// Matches default adc range
+#ifndef POTENTIOMETER_RAW_MIN_VALUE
+#    define POTENTIOMETER_RAW_MIN_VALUE 0
+#endif
+#ifndef POTENTIOMETER_RAW_MAX_VALUE
+#    define POTENTIOMETER_RAW_MAX_VALUE (1 << 10)
+#endif
+
+static pin_t potentiometer_pads[] = POTENTIOMETER_PINS;
+#define NUM_POTENTIOMETERS (ARRAY_SIZE(potentiometer_pads))
+
+__attribute__((weak)) void potentiometer_driver_init(void) {
+    // do nothing
+}
+
+__attribute__((weak)) uint16_t potentiometer_driver_sample(uint8_t index) {
+    return analogReadPin(potentiometer_pads[index]);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// Callbacks
+
+__attribute__((weak)) bool potentiometer_update_user(uint8_t index, uint16_t value) {
+    return true;
+}
+
+__attribute__((weak)) bool potentiometer_update_kb(uint8_t index, uint16_t value) {
+    return potentiometer_update_user(index, value);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// Default scanning routine
+
+__attribute__((weak)) uint16_t potentiometer_map(uint8_t index, uint16_t value) {
+    (void)index;
+
+    uint32_t a   = POTENTIOMETER_OUTPUT_MIN_VALUE;
+    uint32_t b   = POTENTIOMETER_OUTPUT_MAX_VALUE;
+    uint32_t min = POTENTIOMETER_RAW_MIN_VALUE;
+    uint32_t max = POTENTIOMETER_RAW_MAX_VALUE;
+
+    // Scale value to min/max using the adc range
+    return ((b - a) * (value - min) / (max - min)) + a;
+}
+
+__attribute__((weak)) bool potentiometer_filter(uint8_t index, uint16_t value) {
+    // ADC currently limited to max of 12 bits - init to max 16 ensures
+    // we can correctly capture even a raw first sample at max adc bounds
+    static uint16_t potentiometer_state[NUM_POTENTIOMETERS] = {UINT16_MAX};
+
+    if (value == potentiometer_state[index]) {
+        return false;
+    }
+
+    potentiometer_state[index] = value;
+    return true;
+}
+
+__attribute__((weak)) bool potentiometer_throttle_task(void) {
+#if (POTENTIOMETER_THROTTLE_MS > 0)
+    static uint32_t last_exec = 0;
+    if (timer_elapsed32(last_exec) < POTENTIOMETER_THROTTLE_MS) {
+        return false;
+    }
+    last_exec = timer_read32();
+#endif
+    return true;
+}
+
+void potentiometer_init(void) {
+    potentiometer_driver_init();
+}
+
+bool potentiometer_task(void) {
+    if (!potentiometer_throttle_task()) {
+        return false;
+    }
+
+    bool changed = false;
+    for (uint8_t index = 0; index < NUM_POTENTIOMETERS; index++) {
+        uint16_t raw   = potentiometer_driver_sample(index);
+        uint16_t value = potentiometer_map(index, raw);
+        if (potentiometer_filter(index, value)) {
+            changed |= true;
+
+            potentiometer_update_kb(index, value);
+        }
+    }
+
+    return changed;
+}

quantum/potentiometer.h

@@ -0,0 +1,18 @@
+// Copyright 2023 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/** \brief user hook called when sampled value has changed
+ */
+bool potentiometer_update_user(uint8_t index, uint16_t value);
+
+/** \brief keyboard hook called when sampled value has changed
+ */
+bool potentiometer_update_kb(uint8_t index, uint16_t value);
+
+/** \brief Handle various subsystem background tasks
+ */
+bool potentiometer_task(void);

quantum/quantum.h

@@ -207,6 +207,10 @@ extern layer_state_t layer_state;
 #    include "encoder.h"
 #endif
 
+#ifdef POTENTIOMETER_ENABLE
+#    include "potentiometer.h"
+#endif
+
 #ifdef POINTING_DEVICE_ENABLE
 #    include "pointing_device.h"
 #endif