電子信息專業(yè)畢業(yè)設(shè)計(jì)外文資料翻譯--sja1000獨(dú)立的can控制器應(yīng)用指南-電子信息-展示頁
2025-05-26 20:53本頁面
【正文】 Architecture Generally each CAN module can be divided into different functional blocks. The connection to the CAN bus lines is usually built with a CAN Transceiver optimized for the applications [3], [4], [5]. The transceiver controls the logic level signals from the CAN controller into the physical levels on the bus and vice versa. The next upper level is a CAN Controller which implements the plete CAN protocol defined in the CAN Specification [8]. Often it also covers message buffering and acceptance filtering. All these CAN functions are controlled by a Module Controller which performs the functionality of the application. For example, it controls actuators, reads sensors and handles the manmachine interface (MMI). As shown in Figure 1 the SJA1000 standalone CAN controller is always located between a microcontroller and the transceiver, which is an integrated circuit in most cases. 9 Block Diagram The following figure shows the block diagram of the SJA1000. The CAN Core Block controls the transmission and reception of CAN frames according to the CAN specification. The Interface Management Logic block performs a link to the external host controller which can be a microcontroller or any other device. Every register access via the SJA1000 multiplexed address/data bus and controlling of the read/write strobes is handled in this unit. Additionally to the BasicCAN functions known from the PCA82C200, new PeliCAN features have been added. As a consequence of this, additional registers and logic have been implemented mainly in this block. The Transmit Buffer of the SJA1000 is able to store one plete message (Extended or Standard). Whenever a transmission is initiated by the host controller the Interface Management Logic forces the CAN Core Block to read the CAN message from the Transmit Buffer. When receiving a message, the CAN Core Block converts the serial bit stream into parallel data for the Acceptance Filter. With this programmable filter the SJA1000 decides which messages actually are received by the host controller. All received messages accepted by the acceptance filter are stored within a Receive FIFO. Depending on the mode of operation and the data length up to 32 messages can be stored. This enables the user to be more flexible when specifying interrupt services and interrupt priorities for the system because the probability of data overrun conditions is reduced extremely. 10 3. SYSTEM For connection to the host controller, the SJA1000 provides
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