AN2633 Freescale Semiconductor / Motorola, AN2633 Datasheet - Page 26

• Manufacturer Part Number: AN2633
• Description: LIN Drivers for SLIC Module on the MC68HC908QL4
• Manufacturer: Freescale Semiconductor / Motorola

Freescale Semiconductor, Inc.
AN2633/D
The difference in the number of interrupts serviced is best seen on an
oscilloscope showing the ISR pulses.
Figure 12
shows the interrupts required
to service an 8-byte request message at 9600bps.
Figure 12. 8-Byte LIN Request Message and Interrupt Handling
for HC908QY4, HC908EY16, and HC908QL4
Channel 1 shows the LIN message as seen at the RX pin of the QL4 slave
device. Channel R1 is a stored waveform showing the 106 interrupts required
to bit bang the message. The interrupts seem to extend past the end of the
message frame, but this is due to the delay between the ID lookup and the
beginning of the slave's response. Channel R2 is also a stored waveform
showing the 12 interrupts required for an EY16 based slave. Channel 3 shows
the 2 interrupts required by the QL4 slave node with the SLIC module.
This performance data suggests that the QL4 and EY16 MCUs are better
suited for CPU-intensive applications (such as motor control). For simpler, less
time-critical applications (such as contact monitoring), the QY4 should be
sufficient. MCU selection must be made by balancing cost and resource
requirements of CPU and memory.
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LIN Drivers for SLIC Module on the MC68HC908QL4
MOTOROLA
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