1.. _can_transceiver_api:
2
3CAN Transceiver
4###############
5
6.. contents::
7    :local:
8    :depth: 2
9
10Overview
11********
12
13A CAN transceiver is an external device that converts the logic level signals
14from the CAN controller to the bus-levels. The bus lines are called
15CAN High (CAN H) and CAN Low (CAN L).
16The transmit wire from the controller to the transceiver is called CAN TX,
17and the receive wire is called CAN RX.
18These wires use the logic levels whereas the bus-level is interpreted
19differentially between CAN H and CAN L.
20The bus can be either in the recessive (logical one) or dominant (logical zero)
21state. The recessive state is when both lines, CAN H and CAN L, are roughly at
22the same voltage level. This state is also the idle state.
23To write a dominant bit to the bus, open-drain transistors tie CAN H to Vdd
24and CAN L to ground.
25The first and last node use a 120-ohm resistor between CAN H and CAN L to
26terminate the bus. The dominant state always overrides the recessive state.
27This structure is called a wired-AND.
28
29.. image:: transceiver.svg
30   :width: 70%
31   :align: center
32   :alt: CAN Transceiver
33
34CAN Transceiver API Reference
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36
37.. doxygengroup:: can_transceiver
38