Controller Area Network (CAN) - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 689

10 29 s/m
Microchip MCP2551 transceiver and receiver propagation delay 5 150 ns at 85°C
Oscillator frequency 5 bus frequency 5 24 MHz
E13.2 Calculate the bit segments for the following system constraints assuming that the
Microchip MCP2551 transceiver is used:
Bit rate 5 200 kbps
Bus length 5 100 m
Bus propagation delay 5 5

Bus propagation delay 5 5 ×

10 29 s/m
Microchip MCP2551 transceiver and receiver propagation delay 5 150 ns at 85°C
Oscillator frequency 5 bus frequency 5 24 MHz
E13.3 Calculate the bit segments for the following system constraints assuming that the
Microchip MCP2551 transceiver is used:
Bit rate 5 1 Mbps
Bus length 5 20 m
Bus propagation delay 5 5

×

10 29 s/m
MCP2551 transceiver and receiver propagation delay 5 150 ns at 85°C
Oscillator frequency 5 bus frequency 5 32 MHz
E13.4 Calculate the bit segments for the following system constraints assuming that the
Microchip MCP2551 transceiver is used:
Bit rate 5 800 kbps
Bus length 5 20 m
Bus propagation delay 5 5

×

10 29 s/m
MCP2551 transceiver and receiver propagation delay 5 150 ns at 85°C
Oscillator frequency 5 16 MHz (PLL is used to convert to 24-MHz bus frequency)
E13.5 Write a subroutine to confi gure the CAN1 module of the HCS12DP256 with the bit
timing parameters computed in E13.2. Enable receive interrupt but disable transmit interrupt.
Confi gure the CAN so that it accepts only messages with the extended or standard identifi ers
starting with H, P, or T. Use an 8-bit fi lter to control the acceptance.
E13.6 Write a C function to perform the same setting as in E13.4.
E13.7 Provide three different ways of accepting messages that have the letter K as the fi rst letter
of the identifi er.
E13.8 Write an assembly program to send out the string “Monday” using WD as the fi rst two
characters of the extended identifi er. The remaining bits of the identifi er are cleared to 0.
E13.9 Write a C program to send out the string “too high” using ans as the fi rst three letters of
the extended identifi er. The remaining bits of the extended identifi er are cleared to 0.

×

13.16 Lab Exercises and Assignments

L13.1 Practice data transfer over the CAN bus using the following procedures:
Step 1
Use a pair of insulated wires about 20 m long. Connect the CAN_H pins of two demo boards
(e.g., the SSE256 or Dragon12 demo boards) with one wire and connect the CAN_L pins of