34 lines
1.4 KiB
Markdown
34 lines
1.4 KiB
Markdown
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# CAN Self Test Example
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## Overview
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The CAN Self Test Example demonstrates the self testing capabilities of the
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ESP32 CAN peripheral and **only requires a single ESP32 module to run**.
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The Self Test Example can be used to verify that the wiring between the ESP32
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and an external transceiver operates correctly.
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The CAN Self Test Example will do the following over multiple iterations:
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1. Start the CAN driver
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2. Simultaneously transmit and receive messages using the self reception request.
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3. Stop the CAN driver
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## External Transceiver and Pin Assignment
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The CAN controller in the ESP32 **does not contain an internal transceiver**.
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Therefore users are responsible for providing an external transceiver compatible
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with the physical layer specifications of their target ISO standard (such as
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SN65HVD23X transceivers for ISO 11898-2 compatibility)
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The CAN controller in the ESP32 represents dominant bits to the transceiver as
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logic low, and recessive bits as logic high. The Self Test Example utilizes the
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following default pin assignments
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* TX Pin is routed to GPIO21
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* RX Pin is routed to GPIO22
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## Note
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If the Self Test Example does not receive any messages, it is likely that the
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wiring between the ESP32 and the external transceiver is incorrect. To verify
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that the CAN controller in the ESP32 is operating correctly, users can bypass
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the external transceiver by connecting the TX Pin directly to the RX Pin when
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running the Self Test Example.
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