Subject to certain rules, every module can transmit its messages at
a time determined by itself. All modules are of equal status; in
other words, none is either a master or a slave. Since one of
Volcano’s most important functions is to eliminate conflicts and
queues on the networks, the priority and maximum permissible
time delay of every message have been determined by the system
designers. This affords full control over all signals transmitted
over the networks.
在傳統的系統中，每個模塊能夠自己決定發送信息的時間，所有的模塊處在同一個平等狀態。換句話說，他們之間沒有主從關係。Volcano的一個最主要的功能就是減少網絡的信息衝突，系統設計者可以決定每條信息的優先級和允許的延遲時間。這些可以整個控制網絡上的信息傳輸。
To minimise the number of costly variants, each electronic module is produced only in a single hardware version which is suitable for all cars based on the new electrical
platform. The standardised hardware is used for all types of function. Although a range of microprocessors capable of handling CAN communications is available on the market, these are not optimised for Volvo’s Volcano communications specification. To overcome this problem, Volvo collaborated with semiconductor manufacturer Motorola to develop a type designed specifically for its requirements. Bearing the designation 68HC08, this device is now a standard Motorola product and is used in about ten electronic modules in various parts of the car.
爲最小化成本，每個每個電子模塊生產的時候都是一個單一的硬件版本社和所有新電子平臺的汽車。標準的硬件使用所有的功能。雖然市場上有一系列的產品能夠處理CAN通訊，但沒有特別適合volcano通訊協議的。爲克服這些問題，volvo和芯片廠商摩托羅拉合作開發一種產品，68HC08，現在這個產品是摩托羅拉的一個標準產品並且用在汽車不同部位的差不多10個電子模塊上。
VNA是高層設計工具，支持CAN、LIN網絡。VNA捕獲網絡上的信息如信號和節點的需求信號。VNA連接着一個保存網絡相關信息的一個數據庫，而且，一個幀編輯器把信息打包成幀，以一個有效的方法利用網絡帶寬。VNA產生配置文件，並用於後來作爲工具鏈中其它工具的輸入。配置文件包括網絡文件、固定文件和目標文件。網絡文件描述網絡接口配置，信號幀產生時間表。固定文件包括每ECU的有效網絡接口和信號。目標文件包括ECUs明確的硬件描述，比如CPU類型和編譯器、存儲數據的內存的大小和地址，象RAM和NVRAM池。
另外一個工具是VTP，用於汽車ECUs。VTP包括兩個部分，VCFG，是一個被ECU開發商、系統集成商使用配置工具，Volcano庫。olvano庫是CAN和LIN通訊時需要的一個前編譯目標庫。VCFG採集網絡文件和固定文件，（產生於VNA）
。VCFG產生連接olvano庫的目標依賴代碼，或者其它庫或者應用程序源文件for特殊的ECU。編譯器和連接器產生包含ECU通信行爲的目標image。最後，VTP通過軟件下載工具Volcano boot－loader把image下載到ECU中。下載的軟件必須和ECU中已經存在的軟件兼容。
2.6 The Target Hardware
Embedded systems are usually based on a microcontroller which is an integrated microprocessor and a set of peripherals, including an external bus and memories. There are common examples of processor families such as ARM, StrongARM, PowerPC, Motorola 68k and MIPS. The best-selling 32-bit microcontroller of these is the ARM family from Advanced Risc Machines. All ARM variants have a single, simple pipeline, and very few have caches. The second-best selling architecture is the Motorola 68k family to which the current used microcontroller MC9S12DP256 belongs.
Volcano
Volcano was described at the meeting on 31/10/01 as “TTP on CAN” and the Volcano website [16] describes the protocol as CAN-based and deterministic. The protocol is used by Volvo on the S80 and V70, and is coming into use on Volvo buses.
時間觸發的CAN
According to my reading of the Volcano Communications Concept [17], Volcano appears to be a technique in which the CAN network is integrated in such a way as to guarantee the latency of all the messages. It does this by specifying the latency and periodicity of messages at design time. This allows the maximum latencies to be calculated, so the system integrator (designer) can specify the network set up in such a way as to juggle these specifications to guarantee the specified parameters, by avoiding arbitration as far as possible. This seems to imply that the sending of network communication is time triggered rather than event triggered, so the description “TTP on CAN” seems a pretty good summing up.
確定所有信息的延時，在設計階段明確信息的延時和週期。通過明確信息來儘量避免仲裁。
This apparently means that network loadings can be considerably higher than using CAN conventionally, maybe 60% loading, whereas for latency of lower priority messages to be contained to reasonable limits, CAN loading may need to be around 10%.
負載率60％降到10％
