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remote.md

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Remote Protocol

Overview

The remote protocol is an extension of the existing programmer/radio communication protocol. Please review that protocol first before proceeding.

Remote Mode Activation

To activate remote mode on the radio, send a single-byte packet with ID 0x4A. To deactivate remote mode, send 0x4B. Upon receiving either of these packets, the radio will acknowledge by echoing back the same ID byte to the host.

Radio to Host Packets

The following packets are sent from the radio to the host:

Display Text (Packet ID: 0x64)

struct {
    u8 ID;       // 0x64
    u8 fontSize; // 0 - Small (6x8), 1 = Medium (8x8), 2 = Large (8x16), 3 = Huge (16x16)
    u8 x;        // Location
    u8 y;
    u16 fgColor; // Foreground color (see Color Encoding below)
    u16 bgColor; // Background color
    char text[]; // Null-terminated variable-length string
} displayTextPacket;

Draw Rectangle (Packet ID: 0x65)

struct {
    u8 ID;       // 0x65
    u8 x;        // Location
    u8 y;
    u8 width;
    u8 height;
    u16 color;   // Color (see Color Encoding below)
} drawRectanglePacket;

Draw Custom Symbol (Packet ID: 0x66)

struct {
    u8 ID;       // 0x66
    u8 symbolID;
    u8 x;        // Location
    u8 y;
    u16 fgColor; // Foreground color (see Color Encoding below)
    u16 bgColor; // Background color
} drawSymbolPacket;

Custom Symbol IDs

Symbol ID Description
0x00 Dual Watch Icon
0x01 Busy Lock Icon
0x02 Music Note (not used)
0x03 Right Arrow
0x04 Up Arrow
0x05 Down Arrow
0x06 VOX Icon
0x07 Keylock Icon
0x08 Scan Icon
0x09 Long Press Shift Icon
0x0A NO
0x0B AA (forms NOAA icon)
0x0D Bluetooth Icon
0x0E Blank Symbol (for erasing)
0x0F Pause Icon

Signal Strength (Packet ID: 0x67)

struct {
    u8 ID;              // 0x67
    u8 signalStrength;  // Range: 0-120 (values >120 capped to 120)
    u8 mode;            // 0=Rx, 1=Tx
} signalStrengthPacket;

External Noise Level (Packet ID: 0x68)

struct {
    u8 ID;         // 0x68
    u8 noiseLevel; // Range: 0-120 (values >120 capped to 120)
    u8 mode;       // 0=Rx, 1=Tx (tx mod meter)
} noiseLevelPacket;

Signal Bar Vertical Position (Packet ID: 0x69)

struct {
    u8 ID;      // 0x69
    u8 sigBarY; // Vertical position of the signal bar
} signalBarPosPacket;

LED Status (Packet IDs: 0x70 - 0x7F)

These single-byte packets control LED status. The lower 4 bits represent LED states:

  • Bit 0 = Left Green LED
  • Bit 1 = Left Red LED
  • Bit 2 = Right Green LED
  • Bit 3 = Right Red LED
  • 1 = ON, 0 = OFF

Color Encoding

Colors are encoded as 16-bit values using the BGR 565 format:

Bit: FEDCBA9876543210
     BBBBBGGGGGGRRRRR
  • B (Blue): 5 bits
  • G (Green): 6 bits
  • R (Red): 5 bits
typedef union
{
    u16 value;
    struct
    {
        u16 r : 5;
        u16 g_lo : 3; // needs to be split as C Compilers don't like bit fields that span byte boundaries
        u16 g_hi : 3;
        u16 b : 5;
    } RGB;
    struct
    {
        // c2 = bbbbbggg
        // c1 = gggrrrrr
        u8 c1;
        u8 c2;
    } bytes;
} COLOR;

Host to Radio Packets

The host sends single-byte packets that represent keypad presses. The radio responds as if a physical key was pressed or released.

Key Press Events (Packet IDs: 0x80 - 0x93)

Packet ID Key
0x80 - 0x89 Keys 0 - 9
0x8A Menu Key
0x8B Up Key
0x8C Down Key
0x8D Exit Key
0x8E * Key
0x8F # Key
0x90 PTT-A Key
0x91 PTT-B Key
0x92 Flashlight Key
0x93 PTT-E Key (external mic PTT)

Key Release Event (Packet ID: 0xFF)

  • 0xFF = No Key (release)
  • The radio only processes one key press at a time.

Desync Protection

To ensure smooth and uninterrupted communication between the Radio and the Host, every packet transmitted from the Radio to the Host is padded with two additional null bytes (0x00) at the end, with the exception of LED status update packets. These extra bytes serve as no-operation (NOP) bytes, meaning they do not carry any meaningful data and can be safely ignored by the Host system. For more technical details on their handling, refer to the main protocol documentation.

The primary purpose of these extra bytes is to provide a desynchronization buffer that compensates for occasional or sporadic data loss. In real-time communication systems, data bytes may occasionally be dropped, which can cause desynchronization between the Radio and the Host. By adding the padding, these null bytes act as a safeguard, effectively "replacing" the lost bytes. This ensures that synchronization is maintained even when some bytes are lost during transmission.

When such events occur, users may experience a minor visual glitch on the display as a temporary consequence of the lost data. However, the additional padding ensures that the overall communication between the Radio and the PC remains in sync, preventing any lasting or significant disruptions. This technique helps avoid issues such as timing mismatches or data misalignment, which could otherwise impact the performance or visual consistency of the system.

While the NOP bytes are not necessary for the actual data payload, they offer a layer of robustness to the system, improving its resilience against imperfections in the transmission process and reducing the likelihood of noticeable performance degradation. The result is a more stable and reliable data stream between the Radio and the Host, minimizing the impact of sporadic byte loss.

Notes

  • The remote control operates as an extension of the main programmer/radio protocol.
  • The radio acknowledges activation (0x4A) and deactivation (0x4B) requests by echoing them back.
  • The radio can only register one key press at a time.

This structured format ensures clarity and easy reference for developers implementing or integrating the remote protocol.