feat: add support for Latch Relay

Author: facchinm

examples/Modulino_LatchRelay/LatchRelay_Basic/LatchRelay_Basic.ino

@@ -0,0 +1,45 @@
+/*
+ * Modulino Latch Relay - Basic
+ *
+ * This example code is in the public domain. 
+ * Copyright (c) 2025 Arduino
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+#include <Modulino.h>
+
+ModulinoLatchRelay relay;
+
+void setup() {
+  // put your setup code here, to run once:
+  Modulino.begin();
+  Serial.begin(115200);
+  relay.begin();
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+  if (Serial.available()) {
+    char c = Serial.read();
+    switch (c) {
+      case 's':
+        relay.set();
+        break;
+      case 'r':
+        relay.reset();
+        break;
+      case 'x':
+        auto status = relay.getStatus();
+        if (status == 0) {
+          Serial.println("Relay OFF");
+        }
+        if (status == 1) {
+          Serial.println("Relay ON");
+        }
+        if (status < 0) {
+          Serial.println("Relay status unknown");
+        }
+        break;
+    }
+  }
+}

examples/Utilities/FirmwareUpdater/FirmwareUpdater.ino

@@ -294,7 +294,7 @@ final_ack:
 int sendReset() {
   uint8_t buf[3] = { 'D', 'I', 'E' };
   int ret;
-  for (int i = 8; i < 0x78; i++) {
+  for (int i = 0; i < 0x78; i++) {
     modulino.getWire()->beginTransmission(i);
     ret = modulino.getWire()->endTransmission();
     if (ret != 2) {

src/Modulino.h

@@ -639,10 +639,10 @@ class ModulinoDistance : public Module {
   _distance_api* api = nullptr;
 };
 
-class ModulinoRelay : public Module {
+class ModulinoOptoRelay : public Module {
 public:
-  ModulinoRelay(uint8_t address = 0xFF)
-    : Module(address, "RELAY") {}
+  ModulinoOptoRelay(uint8_t address = 0xFF)
+    : Module(address, "OPTO_RELAY") {}
   bool update() {
     uint8_t buf[3];
     auto res = read((uint8_t*)buf, 3);
@@ -686,4 +686,57 @@ class ModulinoRelay : public Module {
   uint8_t match[1] = { 0x28 };  // same as fw main.c
 };
 
+class ModulinoLatchRelay : public Module {
+public:
+  ModulinoLatchRelay(uint8_t address = 0xFF)
+    : Module(address, "REL") {}
+  bool update() {
+    uint8_t buf[3];
+    auto res = read((uint8_t*)buf, 3);
+    auto ret = res && (buf[0] != last_status[0] || buf[1] != last_status[1] || buf[2] != last_status[2]);
+    last_status[0] = buf[0];
+    last_status[1] = buf[1];
+    last_status[2] = buf[2];
+    return ret;
+  }
+  void set() {
+    uint8_t buf[3];
+    buf[0] = 1;
+    buf[1] = 0;
+    buf[2] = 0;
+    write((uint8_t*)buf, 3);
+    return;
+  }
+  void reset() {
+    uint8_t buf[3];
+    buf[0] = 0;
+    buf[1] = 0;
+    buf[2] = 0;
+    write((uint8_t*)buf, 3);
+    return;
+  }
+  int getStatus() {
+    update();
+    if (last_status[0] == 0 && last_status[1] == 0) {
+      return -1; // unknown, last status before poweroff is maintained
+    } else if (last_status[0] == 1) {
+      return 0; // off
+    } else {
+      return 1; // on
+    }
+  }
+  virtual uint8_t discover() {
+    for (unsigned int i = 0; i < sizeof(match)/sizeof(match[0]); i++) {
+      if (scan(match[i])) {
+        return match[i];
+      }
+    }
+    return 0xFF;
+  }
+private:
+  bool last_status[3];
+protected:
+  uint8_t match[1] = { 0x04 };  // same as fw main.c
+};
+
 #endif