sequence-diagrams.puml

@startuml sequence-diagram

actor User
participant Requester as a
participant Holder as b
participant 2nd_requester as c

group Startup
    a -> a: Generate ID
    a -> a: Ramp up radio\nin RX
    a -> a: Init GPIO
end

group User action
    User -> a: Button1 press
    a -> a: Check if\nholding LED1

    alt Holding 1
        note over a: No action
    else Not holding 1
        a -> a: Switch to TX
        a -> b: LED req(IDa, LED1)
        a -> a: Switch to RX
        a -> a: Begin timer
    end

end

group Holder receives request
    a -> b: LED req(IDa, LED1)
    b -> b: Check if\nholding LED1

    alt Holding 1
        b -> b: LED1 off
        b -> b: Switch to TX
        b -> a: LED res(IDa, LED1)
        b -> b: Switch to RX
    else Not holding 1
        note over b: No action
    end

    b -> b: Compare IDa and IDb

    alt IDa == IDb
        b -> b: Generate new ID
    else IDa != IDb
        note over b: No action
    end

end

group Requester receives response
    b -> a: LED res(IDa, LED1)
    a -> a: LED1 on
    a -> a: Cancel timer
    a -> a: Reset retries
end

group Timer timeout

    alt Retries < 3
        a -> a: Switch to TX
        a -> b: LED req(IDa, LED1)
        a -> a: Switch to RX
        a -> a: Begin timer
        a -> a: Increment retries
    else
        a -> a: LED1 on
        a -> a: Reset retries
    end
    
end

group Requester detects another request
    c -> a: LED req(IDc, LED1)
    a -> a: Drop request
    a -> a: Compare IDa and IDc

    alt IDa == IDc
        a -> a: Generate new ID
    else
        note over a: No action
    end

end

@enduml