Disable ACK in can-bus when using can.h

Projects Networking, Protocols, and Devices
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I'm using the can.h library to make a can-bus sniffer. Now I noticed that after a frame the ESP (ESP32-WROOM-32D dev kit) sends an ACK. As I'm just making a sniffer and don't want to influence the signal flow, I wanted to disable this ACK so I disconnected Tx from the transciever (SN65HVD230 CAN bus transceiver), but then the receiver doesn't work anymore, it will not receive any frames anymore. Is the can.h library checking if it's ACK is really send?
Is there a listen-only mode in can.h? I can't find it

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Hi @reinierdevlaam ,

there seems to be a "silent mode" for specific CANbus Transceivers:

See here (Search the page for "silent"): https://www.circuitstate.com/tutorials/what-is-can-bus-how-to-use-can-interface-with-esp32-and-arduino/

and here https://www.ti.com/lit/an/slla442/slla442.pdf?ts=1736761710016&ref_url=https%253A%252F%252Fwww.ti.com%252Finterface%252Fcan-transceivers%252Foverview.html

or here https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/ATA6564-High-Speed-CAN-Transceiver-with-Silent-Mode-20005784D.pdf

Unfortunately this does not seem to apply to a SN65HVD230 :

https://www.ti.com/lit/ds/symlink/sn65hvd230.pdf?ts=1736791722632&ref_url=https%253A%252F%252Fwww.google.com%252F

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this library, supports listening mode.

hope that helps....

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The MCP2515 CAN module I use features a passive mode that ignores all filters and receives all messages on the bus. I expect the ESP also supports this functionality. However, since I am not familiar with your library, this is the best guidance I can provide.

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