[Ovmsdev] OVMS CAN-USB Call for Assistance
mark at webb-johnson.net
Wed Sep 4 21:49:46 HKT 2013
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?
> On 4 Sep, 2013, at 4:02 pm, Mastro Gippo <gipmad at gmail.com> wrote:
> 2013/9/4 HONDA S-2000 <s2000 at sounds.wa.com>:
>> If we're going to consider ARM, then I suggest that someone take the time to
>> find out what chips (or circuits) are good candidates for the voltage
>> translation. My hunch is that I/O pins on the ARM do not directly connect to
>> the 12V CAN bus, especially considering that transients of more than 40V
>> might appear. That said, perhaps an ARM solution can be accomplished with
>> the same low chip count as the proposed PIC32 solution.
> What are you talking about? No mcu connects directly to these
> voltages, they all need a transceiver. Also, there is no way we can
> effectively replace the 2551 with passives.. On the other hand, there
> are a bunch of equivalents out there from major companies like TI,
> that may or may not cost less.
> I'd say that the usb connector+MCU+mcp2551+a bunch of passives and a
> crystal is all we need, now it's just a matter of choosing the right
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