SECTION 1INTRODUCTION The MC68HC58 DLC (data link controller) handles microcontroller unit (MCU) to Society of Automotive Engineers (SAE) J1850 bus interface duties. The MC68HC58 DLC is the successor to the MC68HC56 DLCP (data link controller parallel) and the MC68HC57 DLCS (data link controller serial). The MC68HC58 is pin configurable to communicate with a host MCU via an 8-bit non-multiplexed parallel data bus or a Motorola serial peripheral interface. The DLC consists of control logic and bus transceiver circuits. Figure 1-1 shows the internal structure of a DLC configured for parallel mode. Figure 1-2 shows the internal structure of a DLC configured for serial mode. The built-in bus transceiver allows the DLC to be directly connected to the J1850 bus, thus providing a complete link between the central processing unit (CPU) host application and the J1850 bus. The J1850 bus protocol is a method of information transfer via messages (frames) between nodes. A node is any location on the J1850 bus that sends and receives messages. The following are primary features of the DLC: • SAE J1850 compatible • Class 2 (vehicle bus communication protocol) compatible • Handles all network protocol functions (access, arbitration, error detection) • Supports polled or interrupt host DLC servicing • Message buffering on transmit and receive • On-board transceiver with waveshaping • Operates with up to a 2-volt ground offset between network nodes • Pin configurable SPI or parallel host interface • Digitally filtered receiver • Host configurable oscillator divisor • Power conserving sleep feature with fast wakeup on bus or host activity • High voltage CMOS (40 volt HVCMOS) process • Built-in transient and ESD protection The DLC handles SAE J1850 frames with minimal MCU servicing. Each DLC can be operated in either interrupt mode or polled mode. Internal first in/first out (FIFO)buffers, 20 bytes for receiver data and 11 bytes for transmitter data, allow full frame length operations. The MCU typically transfers complete frames to the DLC for transmission on the SAE J1850 bus, and is interrupted only when a complete frame is received from the SAE J1850 bus. The DLC handles all arbitration, error detection,and optional in-frame response duties internally. Changes to the operating configuration can be made at any time. 中国最大的资料库下