435b8a25d6
Split out the CAN transceiver API documentation from the CAN controller API documentation. The CAN transceiver API was introduced in Zephyr v3.1.0. Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
38 lines
1.2 KiB
ReStructuredText
38 lines
1.2 KiB
ReStructuredText
.. _can_transceiver_api:
|
|
|
|
CAN Transceiver
|
|
###############
|
|
|
|
.. contents::
|
|
:local:
|
|
:depth: 2
|
|
|
|
Overview
|
|
********
|
|
|
|
A CAN transceiver is an external device that converts the logic level signals
|
|
from the CAN controller to the bus-levels. The bus lines are called
|
|
CAN High (CAN H) and CAN Low (CAN L).
|
|
The transmit wire from the controller to the transceiver is called CAN TX,
|
|
and the receive wire is called CAN RX.
|
|
These wires use the logic levels whereas the bus-level is interpreted
|
|
differentially between CAN H and CAN L.
|
|
The bus can be either in the recessive (logical one) or dominant (logical zero)
|
|
state. The recessive state is when both lines, CAN H and CAN L, are roughly at
|
|
the same voltage level. This state is also the idle state.
|
|
To write a dominant bit to the bus, open-drain transistors tie CAN H to Vdd
|
|
and CAN L to ground.
|
|
The first and last node use a 120-ohm resistor between CAN H and CAN L to
|
|
terminate the bus. The dominant state always overrides the recessive state.
|
|
This structure is called a wired-AND.
|
|
|
|
.. image:: transceiver.svg
|
|
:width: 70%
|
|
:align: center
|
|
:alt: CAN Transceiver
|
|
|
|
CAN Transceiver API Reference
|
|
*****************************
|
|
|
|
.. doxygengroup:: can_transceiver
|