add modbus (not tested yet)

F1:F103/FX3U/modbusproto.h

@@ -0,0 +1,48 @@
+/*
+ * This file is part of the fx3u project.
+ * Copyright 2024 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "modbusrtu.h"
+#include "strfunc.h"
+
+/*
+MODBUS PROTOCOL:
+uint32_t translates as two uint16_t in big-endian format
+
+MC_READ_COIL - coil values (by bits)
+MC_READ_DISCRETE - discrete -//-
+MC_READ_HOLDING_REG - read time/led/inch/outch
+MC_READ_INPUT_REG - read ADC channel (regno is ADC ch number)
+MC_WRITE_COIL - change single relay
+MC_WRITE_REG - set/reset LED, restart MCU
+MC_WRITE_MUL_COILS - change several relays
+MC_WRITE_MUL_REGS - change Tms
+*/
+
+// holding registers list (comment - corresponding CANbus command)
+typedef enum{
+    MR_RESET,           // CMD_RESET
+    MR_TIME,            // CMD_TIME
+    MR_LED,             // CMD_LED
+    MR_INCHANNELS,      // CMD_INCHNLS
+    MR_OUTCHANNELS,     // CMD_OUTCHNLS
+} modbus_registers;
+
+void parse_modbus_request(modbus_request *r);
+void parse_modbus_response(modbus_response *r);