Add a basic i2c gpio expander implementation

1 files changed, 67 insertions, 0 deletions

diff --git a/main/gpio-expander.cpp b/main/gpio-expander.cpp
new file mode 100644
index 00000000..3aadb63e
--- /dev/null
+++ b/main/gpio-expander.cpp
@@ -0,0 +1,67 @@
+#include "gpio-expander.h"
+
+namespace gay_ipod {
+
+GpioExpander::GpioExpander() {
+}
+
+GpioExpander::~GpioExpander() {
+}
+
+esp_err_t GpioExpander::Write() {
+  i2c_cmd_handle_t handle = i2c_cmd_link_create();
+  if (handle == NULL) {
+    return ESP_ERR_NO_MEM;
+  }
+
+  // Technically enqueuing these commands could fail, but we don't worry about
+  // it because that would indicate some really very badly wrong more generally.
+  i2c_master_start(handle);
+  i2c_master_write_byte(handle, (PCA8575_ADDRESS << 1 | I2C_MASTER_WRITE), true);
+  i2c_master_write_byte(handle, port_a_, true);
+  i2c_master_write_byte(handle, port_b_, true);
+  i2c_master_stop(handle);
+
+  // TODO: timeout
+  esp_err_t ret = i2c_master_cmd_begin(0, handle, 0);
+
+  i2c_cmd_link_delete(handle);
+  return ret;
+}
+
+esp_err_t GpioExpander::Read() {
+  i2c_cmd_handle_t handle = i2c_cmd_link_create();
+  if (handle == NULL) {
+    return ESP_ERR_NO_MEM;
+  }
+
+  // Technically enqueuing these commands could fail, but we don't worry about
+  // it because that would indicate some really very badly wrong more generally.
+  i2c_master_start(handle);
+  i2c_master_write_byte(handle, (PCA8575_ADDRESS << 1 | I2C_MASTER_READ), true);
+  i2c_master_read_byte(handle, &input_a_, I2C_MASTER_ACK);
+  i2c_master_read_byte(handle, &input_b_, I2C_MASTER_LAST_NACK);
+  i2c_master_stop(handle);
+
+  // TODO: timeout
+  esp_err_t ret = i2c_master_cmd_begin(0, handle, 0);
+
+  i2c_cmd_link_delete(handle);
+  return ret;
+}
+
+bool GpioExpander::charge_power_ok(void) {
+  // Active-low.
+  return (input_a_ & (1 << 4)) == 0;
+}
+
+bool GpioExpander::headphone_detect(void) {
+  // Active-low.
+  return (input_b_ & (1 << 0)) == 0; // TODO.
+}
+
+uint8_t GpioExpander::key_states(void) {
+  return input_b_ & 0b00111111;
+}
+
+} // namespace gay_ipod