Function build_long_request 

pub fn build_long_request(
    device_index: u8,
    feature_index: u8,
    function_id: u8,
    params: &[u8],
) -> [u8; 20]

Builds a long HID++ request (20 bytes).

Arguments

• device_index - Device index (0xFF for direct, 1-6 for receiver)
• feature_index - Feature index from feature discovery
• function_id - Function ID within the feature
• params - Optional parameters (max 16 bytes)