From: Neil <picdude3@narwani.org>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Sat, 4 Jan 2020 22:39:14 -0800
Subject: [EE] MCP2551 CANbus driver behaviour
Thread-Topic: [EE] MCP2551 CANbus driver behaviour
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Hi,

Tinkering with an MCP2551 CAN driver chip on a breadboard and the=20
behaviour is not what I expect...
First, I've got 5V and ground to Vdd and Vss resp., a 20k resistor on Rs=20
to ground, and a 120-ohm resistor across CANH and CANL.
Second, the datasheet is here...=20
http://ww1.microchip.com/downloads/en/DeviceDoc/20001667G.pdf

Table 1-2 (truth table) says that I should get a differential voltage=20
(~2V as per CAN spec) when TXD is low, and I expect that it will be=20
continuous, but I get a spike for a few ms (haven't actually measured=20
the time)

What an I missing or misinterpreting here?

Cheers,
-Neil.


--=20
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