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I am a novice designer who recently started designing circuits.

Using the STM32f407VGT MCU operating at 3.3V, using the CAN1TX(PB9) CAN1RX(PB8) pins, the circuit was configured by referring to NXP's TJA1042T/3 High Speed ​​Can Transceiver datasheet, which can also operate at 3.3V logic.

Based on the configured circuit, I recognized the problem that CAN data was not output while debugging using the CAN communication equipment of Peak System.

As a result of hardware debugging, I know that the existing High Speed ​​CAN communication method operates at 3.5V and 1.5V for CAN H based on 2.5V.

In my circuit, the standard for 2.5V is the same, but CAN H is about We have identified a problem that operates at 3.9V, CAN L about 1.1V.

Maybe there is something wrong with my circuit?

enter image description here

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  • \$\begingroup\$ To add one thing, the differential voltage of CAN communication should come out to be 2V, but my board has a problem that it comes out close to 3V. \$\endgroup\$
    – 이동재
    Commented Jul 17, 2021 at 12:42
  • \$\begingroup\$ Hardware seems fine. Do you see some standard signal on the TX pin of you MCU ? What CAN frequency did you set ? (The same in firmware as the one on PCAN-View ?) \$\endgroup\$
    – Mathieu G.
    Commented Jul 17, 2021 at 21:10
  • \$\begingroup\$ Using STM32F407VG6 chip, APB1 Clock was set to 24Mhz. Prescaler was set to 3, Time Quantum to 125.0ns, Bit Segment 1 to 13 Times, and Bit Segment2 to 2 Times. As a result, we set the conditions of 500k bit/s, sample point 87.5%. The PCAN settings were also set the same as above. \$\endgroup\$
    – 이동재
    Commented Jul 18, 2021 at 7:46
  • \$\begingroup\$ I studied CAN communication and thought I got all the settings above, but is there something I'm missing from my knowledge? \$\endgroup\$
    – 이동재
    Commented Jul 18, 2021 at 7:48
  • \$\begingroup\$ What is the bus status displayed by PcanView ? Is the MCU clocked by internal clock ? Do you see a correct 500kbit/s signal on Tx ? I already got the PCAN view unable to see messages because of a bad calibrated internal clock. \$\endgroup\$
    – Mathieu G.
    Commented Jul 18, 2021 at 8:37

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