[Ovmsdev] OVMS CAN-USB Call for Assistance

Mastro Gippo gipmad at gmail.com
Thu Sep 5 04:08:43 HKT 2013

Sorry Brian, I misunderstood what you said, english is not my main
language. As for the mcp2551, it's just a transceiver, you don't need
any libraries. The can logic is embedded in the device. That said, on
the mbed the library allows you to just declare a CAN channel with

CAN can1(p9, p10);

and write a message with :

can1.write(CANMessage(1337, &counter, 1));

see the example on http://mbed.org/handbook/CAN


2013/9/4 HONDA S-2000 <s2000 at sounds.wa.com>:
> The MCP2551 requires a minimum Vdd of 4.5V to ensure ISO-11898
> specifications, but USB Vbus is only guaranteed to be 4.01V under certain
> conditions like at the end of a bus-powered hub.
> There are small 5V boost regulators that work with minimal passives, some
> even with just capacitors and no inductors, but it will add to the size and
> cost.
> Maybe the SN65HVD233 is a better choice. It only tolerates 36V spikes, not
> 42V, but I have no idea how likely either of those high voltages are on a
> CAN bus in real vehicles.
> The SN65HVD233 will tolerate 7V on Vcc, but 3.6V is the maximum recommended.
> I almost suggested that it should run directly from USB Vbus, but that is
> perhaps not wise. I'm sure the 3.3V LDO will handle the load of the CPU and
> CAN transceiver.
> Brian
> On Sep 4, 2013, at 06:49, Mark Webb-Johnson wrote:
>> I'm used to the mcp2551, but it is a 5V device. The pic32mx795 has both
>> CAN port pins 5V tolerant, and levels for tx seem sufficient for mcp2551 to
>> rx. The 5V is not too much of an issue, as we have that from USB, but it
>> would be good to be just 3.3V.
>> Anyone know of a 3.3V equivalent to the mcp2551? SN65HVD233? Or, just stay
>> with mcp2551?
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