chore: mqtt impl, fix more wiznet bugs

include/modbus_master.h

@@ -0,0 +1,56 @@
+#ifndef __MODBUS_MASTER_H
+#define __MODBUS_MASTER_H
+
+#include <stdint.h>
+
+// Function codes
+#define MODBUS_FC_READ_HOLDING_REGISTERS 0x03
+#define MODBUS_FC_WRITE_SINGLE_REGISTER 0x06
+#define MODBUS_FC_WRITE_MULTIPLE_REGISTERS 0x10
+
+// Error codes
+#define MODBUS_ERROR_NONE 0x00
+#define MODBUS_ERROR_FUNCTION 0x01
+#define MODBUS_ERROR_ADDRESS 0x02
+#define MODBUS_ERROR_VALUE 0x03
+#define MODBUS_ERROR_TIMEOUT 0x04
+
+// Frame length
+#define MB_MIN_LEN 4
+#define MB_CRC_LEN 2
+#define MB_WREG_LEN 8
+#define MB_MAX_BUFFER 32
+
+// State machine states
+typedef enum {
+  MODBUS_IDLE,
+  MODBUS_WAITING_RESPONSE,
+  MODBUS_PROCESS_RESPONSE
+} modbus_state_t;
+
+// Modbus context structure
+typedef struct {
+  modbus_state_t state;
+  uint32_t last_send_time;
+  uint32_t response_timeout;
+  uint8_t buffer[MB_MAX_BUFFER];
+  uint16_t rx_len;
+  uint16_t current_bit;
+  uint16_t last_value;
+  void (*on_response)(uint8_t* buf, uint16_t len,
+                      uint16_t value);   // Response callback
+  void (*on_error)(uint8_t error_code);  // Error callback
+} modbus_context_t;
+
+uint16_t modbus_create_request(uint8_t* req, uint8_t slave_addr,
+                               uint8_t function, uint16_t address,
+                               uint16_t value);
+uint8_t modbus_process_response(uint8_t* buf, uint16_t len, uint16_t* value);
+void modbus_init(modbus_context_t* ctx,
+                 void (*response_callback)(uint8_t*, uint16_t, uint16_t),
+                 void (*error_callback)(uint8_t));
+void modbus_set_timeout(modbus_context_t* ctx, uint32_t timeout_ms);
+void modbus_process(modbus_context_t* ctx);
+uint8_t modbus_send_request(modbus_context_t* ctx, uint8_t slave_addr,
+                            uint8_t function, uint16_t address, uint16_t value);
+#endif  // __MODBUS_MASTER_H