dlms.h

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#pragma once
 
#include <cstdint>
 
namespace esphome::dlms_meter {
 
/*
+-------------------------------+
|       Ciphering Service       |
+-------------------------------+
|      System Title Length      |
+-------------------------------+
|                               |
|                               |
|                               |
|            System             |
|            Title              |
|                               |
|                               |
|                               |
+-------------------------------+
|            Length             | (1 or 3 Bytes)
+-------------------------------+
|     Security Control Byte     |
+-------------------------------+
|                               |
|             Frame             |
|            Counter            |
|                               |
+-------------------------------+
|                               |
~                               ~
        Encrypted Payload
~                               ~
|                               |
+-------------------------------+
 
Ciphering Service: 0xDB (General-Glo-Ciphering)
System Title Length: 0x08
System Title: Unique ID of meter
Length: 1 Byte=Length <= 127, 3 Bytes=Length > 127 (0x82 & 2 Bytes length)
Security Control Byte:
- Bit 3…0: Security_Suite_Id
- Bit 4: "A" subfield: indicates that authentication is applied
- Bit 5: "E" subfield: indicates that encryption is applied
- Bit 6: Key_Set subfield: 0 = Unicast, 1 = Broadcast
- Bit 7: Indicates the use of compression.
 */
 
static constexpr uint8_t DLMS_HEADER_LENGTH = 16;
static constexpr uint8_t DLMS_HEADER_EXT_OFFSET = 2;  // Extra offset for extended length header
static constexpr uint8_t DLMS_CIPHER_OFFSET = 0;
static constexpr uint8_t DLMS_SYST_OFFSET = 1;
static constexpr uint8_t DLMS_LENGTH_OFFSET = 10;
static constexpr uint8_t TWO_BYTE_LENGTH = 0x82;
static constexpr uint8_t DLMS_LENGTH_CORRECTION = 5;  // Header bytes included in length field
static constexpr uint8_t DLMS_SECBYTE_OFFSET = 11;
static constexpr uint8_t DLMS_FRAMECOUNTER_OFFSET = 12;
static constexpr uint8_t DLMS_FRAMECOUNTER_LENGTH = 4;
static constexpr uint8_t DLMS_PAYLOAD_OFFSET = 16;
static constexpr uint8_t GLO_CIPHERING = 0xDB;
static constexpr uint8_t DATA_NOTIFICATION = 0x0F;
static constexpr uint8_t TIMESTAMP_DATETIME = 0x0C;
static constexpr uint16_t MAX_MESSAGE_LENGTH = 512;  // Maximum size of message (when having 2 bytes length in header).
 
// Provider specific quirks
static constexpr uint8_t NETZ_NOE_MAGIC_BYTE = 0x81;  // Magic length byte used by Netz NOE
static constexpr uint8_t NETZ_NOE_EXPECTED_MESSAGE_LENGTH = 0xF8;
static constexpr uint8_t NETZ_NOE_EXPECTED_SECURITY_CONTROL_BYTE = 0x20;
 
}  // namespace esphome::dlms_meter