Software
Overview
For Lightning Cat XR2 we naturally developed our own software and related
transmission protocols.
Protocols
In respect of the OSI model, the following diagram shows the layers of
the Lightning Cat XR2 protocols:
Physical layer:
In opposite to other systems, the physical layer
is not defined very closely.
On the one hand, data transmission between controllers and the MCP-computer is
based on RS232C or RS422. On the other hand, transmission between the
MCP-computer and the "Remote Control Center" is based on a
WLAN-IP-UDP-protocol stack or other radio transceivers.
Herewith, "physical layer" is a loose description.
Link layer:
This layer guarantees data integrity and authenticity.
Between controller and MCP-computer this functionality is limited to a simple
checksum algorithm
For data transmissions over Wireless LAN we use relatively secure methods. For example:
- HMAC (keyed-hash message authentication code) to ensure authenticity of
commands
- Sequence numbers and timestamps to ensure the right transmission order and
to avoid replay attacks
The implementation of the link layer depends on
the used transmission method on the physical layer and is located in so-called
transports.
Network layer:
This layer is responsible for dynamic allocation of
addresses to controllers and the routing of commands/responses between all
components.
Application layer:
Beside fixed system functions, that all controllers
must support, each controller naturally implements its own functions to enable
access to its special tasks.
Because of this architecture, it doesn't matter if a real hardware controller
(i.e. switchboard) or a virtual software controller (i.e. watchdog) is controlled.
This means that all comands are identically and transparently processed.
Remote Control Center (RCC)
The Remote Controller Center (RCC) is used to remotely control Lightning
Cat XR2.
It shows all relevant telemetry data (cp. screenshot on the right side):
- Geographical position inclusive cruise speed (GPS receiver inside car)
- Position of gas pedal, brake pedal and steering wheel
- Status of direction indicators, lights, horn etc
Controlling Lightning Cat XR2 is possible with a keyboard, but also with all
DirectX compatible input devices (joysticks, gamepads, steering wheels). Button
and axes functions can be configured to match the personal preferences of the
driver.
We primarily developed a Windows version of the RCC. Adaption to other
architectures (i.e. PDA) is easily possible because of the strict seperation
between screen display, input- and communication subsystem.