MC68HC908GZ8VFA Freescale Semiconductor, MC68HC908GZ8VFA Datasheet - Page 123

• Manufacturer Part Number: MC68HC908GZ8VFA
• Description: IC MCU 8K FLASH 8MHZ CAN 48-LQFP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908GZ8VFA

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: CAN, LIN, SCI, SPI
• Peripherals: LVD, POR, PWM
• Number Of I /o: 37
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

Each CAN station is connected physically to the CAN bus lines through a transceiver chip. The
transceiver is capable of driving the large current needed for the CAN and has current protection against
defected CAN or defected stations.
12.4 Message Storage
MSCAN08 facilitates a sophisticated message storage system which addresses the requirements of a
broad range of network applications.
12.4.1 Background
Modern application layer software is built under two fundamental assumptions:
Above behavior cannot be achieved with a single transmit buffer. That buffer must be reloaded right after
the previous message has been sent. This loading process lasts a definite amount of time and has to be
completed within the inter-frame sequence (IFS) to be able to send an uninterrupted stream of messages.
Even if this is feasible for limited CAN bus speeds, it requires that the CPU reacts with short latencies to
the transmit interrupt.
Freescale Semiconductor
1. Any CAN node is able to send out a stream of scheduled messages without releasing the bus
2. The internal message queue within any CAN node is organized as such that the highest priority
between two messages. Such nodes will arbitrate for the bus right after sending the previous
message and will only release the bus in case of lost arbitration.
message will be sent out first if more than one message is ready to be sent.
MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4
CAN_H
CAN
CAN NODE 1
TRANSCEIVER
CAN CONTROLLER
MCU
TX
(MSCAN08)
Figure 12-2. The CAN System
CAN
CAN_L
RX
CAN BUS
CAN STATION 1
CAN NODE 2
CAN NODE N
Message Storage
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