syntax = "proto3";

package meshtastic;

option csharp_namespace = "Meshtastic.Protobufs";
option go_package = "github.com/meshtastic/go/generated";
option java_outer_classname = "SerialHal";
option java_package = "org.meshtastic.proto";
option swift_prefix = "";

// SerialHalCommand messages are sent from host to device over the SerialHal
// framing stream. Responses normally come back as SerialHalResponse with the
// same transaction_id.
//
// Interrupt notifications are the one asynchronous exception: the device emits
// an unsolicited SerialHalResponse with transaction_id == 0 and value == pin.
// Host implementations should treat those frames as interrupt events rather
// than replies to an outstanding request.

message SerialHalCommand {
  enum Type {
    UNSET = 0;
    PIN_MODE = 1;
    DIGITAL_WRITE = 2;
    DIGITAL_READ = 3;
    ATTACH_INTERRUPT = 4;
    DETACH_INTERRUPT = 5;
    SPI_TRANSFER = 6;
    NOOP = 7;
  }

  // Host-assigned request id. Replies echo this id back in
  // SerialHalResponse.transaction_id.
  uint32 transaction_id = 1;
  Type type = 2;
  uint32 pin = 3;
  uint32 value = 4;
  uint32 mode = 5;
  bytes data = 6;
}

message SerialHalResponse {
  enum Result {
    OK = 0;
    ERROR = 1;
    BAD_REQUEST = 2;
    UNSUPPORTED = 3;
  }

  // Matches the originating SerialHalCommand.transaction_id for normal
  // request/response traffic.
  //
  // A value of 0 indicates an unsolicited interrupt notification generated by
  // the device. In that case, the host should interpret value as the GPIO pin
  // that triggered.
  uint32 transaction_id = 1;
  Result result = 2;
  // Used by DIGITAL_READ replies and interrupt notifications. For interrupt
  // notifications (transaction_id == 0), this carries the pin number.
  uint32 value = 3;
  bytes data = 4;
  string error = 5;
}