[pca9554] Migrate to CachedGpioExpander to reduce I2C bus usage (#10571)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

CODEOWNERS

@@ -342,7 +342,7 @@ esphome/components/ota/* @esphome/core
 esphome/components/output/* @esphome/core
 esphome/components/packet_transport/* @clydebarrow
 esphome/components/pca6416a/* @Mat931
-esphome/components/pca9554/* @clydebarrow @hwstar
+esphome/components/pca9554/* @bdraco @clydebarrow @hwstar
 esphome/components/pcf85063/* @brogon
 esphome/components/pcf8563/* @KoenBreeman
 esphome/components/pi4ioe5v6408/* @jesserockz

esphome/components/pca9554/__init__.py

@@ -11,7 +11,8 @@ from esphome.const import (
     CONF_OUTPUT,
 )
 
-CODEOWNERS = ["@hwstar", "@clydebarrow"]
+CODEOWNERS = ["@hwstar", "@clydebarrow", "@bdraco"]
+AUTO_LOAD = ["gpio_expander"]
 DEPENDENCIES = ["i2c"]
 MULTI_CONF = True
 CONF_PIN_COUNT = "pin_count"

esphome/components/pca9554/pca9554.cpp

@@ -37,10 +37,9 @@ void PCA9554Component::setup() {
 }
 
 void PCA9554Component::loop() {
-  // The read_inputs_() method will cache the input values from the chip.
-  this->read_inputs_();
-  // Clear all the previously read flags.
-  this->was_previously_read_ = 0x00;
+  // Invalidate the cache at the start of each loop.
+  // The actual read will happen on demand when digital_read() is called
+  this->reset_pin_cache_();
 }
 
 void PCA9554Component::dump_config() {
@@ -54,21 +53,17 @@ void PCA9554Component::dump_config() {
   }
 }
 
-bool PCA9554Component::digital_read(uint8_t pin) {
-  // Note: We want to try and avoid doing any I2C bus read transactions here
-  // to conserve I2C bus bandwidth. So what we do is check to see if we
-  // have seen a read during the time esphome is running this loop. If we have,
-  // we do an I2C bus transaction to get the latest value. If we haven't
-  // we return a cached value which was read at the time loop() was called.
-  if (this->was_previously_read_ & (1 << pin))
-    this->read_inputs_();  // Force a read of a new value
-  // Indicate we saw a read request for this pin in case a
-  // read happens later in the same loop.
-  this->was_previously_read_ |= (1 << pin);
+bool PCA9554Component::digital_read_hw(uint8_t pin) {
+  // Read all pins from hardware into input_mask_
+  return this->read_inputs_();  // Return true if I2C read succeeded, false on error
+}
+
+bool PCA9554Component::digital_read_cache(uint8_t pin) {
+  // Return the cached pin state from input_mask_
   return this->input_mask_ & (1 << pin);
 }
 
-void PCA9554Component::digital_write(uint8_t pin, bool value) {
+void PCA9554Component::digital_write_hw(uint8_t pin, bool value) {
   if (value) {
     this->output_mask_ |= (1 << pin);
   } else {
@@ -127,8 +122,7 @@ bool PCA9554Component::write_register_(uint8_t reg, uint16_t value) {
 
 float PCA9554Component::get_setup_priority() const { return setup_priority::IO; }
 
-// Run our loop() method very early in the loop, so that we cache read values before
-// before other components call our digital_read() method.
+// Run our loop() method early to invalidate cache before any other components access the pins
 float PCA9554Component::get_loop_priority() const { return 9.0f; }  // Just after WIFI
 
 void PCA9554GPIOPin::setup() { pin_mode(flags_); }

esphome/components/pca9554/pca9554.h

@@ -3,22 +3,21 @@
 #include "esphome/core/component.h"
 #include "esphome/core/hal.h"
 #include "esphome/components/i2c/i2c.h"
+#include "esphome/components/gpio_expander/cached_gpio.h"
 
 namespace esphome {
 namespace pca9554 {
 
-class PCA9554Component : public Component, public i2c::I2CDevice {
+class PCA9554Component : public Component,
+                         public i2c::I2CDevice,
+                         public gpio_expander::CachedGpioExpander<uint16_t, 16> {
  public:
   PCA9554Component() = default;
 
   /// Check i2c availability and setup masks
   void setup() override;
-  /// Poll for input changes periodically
+  /// Invalidate cache at start of each loop
   void loop() override;
-  /// Helper function to read the value of a pin.
-  bool digital_read(uint8_t pin);
-  /// Helper function to write the value of a pin.
-  void digital_write(uint8_t pin, bool value);
   /// Helper function to set the pin mode of a pin.
   void pin_mode(uint8_t pin, gpio::Flags flags);
 
@@ -32,9 +31,13 @@ class PCA9554Component : public Component, public i2c::I2CDevice {
 
  protected:
   bool read_inputs_();
-
   bool write_register_(uint8_t reg, uint16_t value);
 
+  // Virtual methods from CachedGpioExpander
+  bool digital_read_hw(uint8_t pin) override;
+  bool digital_read_cache(uint8_t pin) override;
+  void digital_write_hw(uint8_t pin, bool value) override;
+
   /// number of bits the expander has
   size_t pin_count_{8};
   /// width of registers
@@ -45,8 +48,6 @@ class PCA9554Component : public Component, public i2c::I2CDevice {
   uint16_t output_mask_{0x00};
   /// The state of the actual input pin states - 1 means HIGH, 0 means LOW
   uint16_t input_mask_{0x00};
-  /// Flags to check if read previously during this loop
-  uint16_t was_previously_read_ = {0x00};
   /// Storage for last I2C error seen
   esphome::i2c::ErrorCode last_error_;
 };