On Sat, 14 Aug 2021 07:49:04 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Sat, 14 Aug 2021 10:03:08 +0100, Michael Kellett <mk@mkesc.co.uk>
>wrote:
>
>>On 13/08/2021 16:25, jlarkin@highlandsniptechnology.com wrote:
>>> A customer wants us to build a box (basically a cinder block bristling
>>> with connectors) that includes a CAN bus for control. We'd include
>>> ethernet too, for more general use.
>>> 
>>> Can someone recommend a good chip or chip set to do slow CAN? A good
>>> eval kit or equivalent? A good way to make a PC talk CAN?
>>> 
>>> We'd have an internal uP, one of the ST Arm things.
>>> 
>>> 
>>> 
>>There are several possible CAN pitfalls, mainly to do with physical 
>>interfaces and protocols.
>>There is low speed fault tolerant CAN and the more common high speed not 
>>fault tolerant CAN. There are ISO specs.
>>Then there are protocols, like CANOpen - but there are zillions of them.
>>
>>The CAN peripheral on the ST chip will probably be OK for anything 
>>hardware except CAN FD. I've known people get fussy about clock speeds 
>>and want "exactly" the odd speed they are using which may not fit well 
>>with the processor clock.
>>
>>If you need to write code to support some of the complex protocols it's 
>>a lot of work.
>>
>>On the other hand if your customer has a sensible and documented home 
>>brew protocol it can be quite simple and problem free.
>>
>>MK
>
>I've been told that ST has software drivers for their CAN interfaces,
>and like their ethernet stuff, it's pretty bad.
>
>We are replacing some old boxes and the customer probably wants them
>to be drop-on replacements for their old home-made stuff. That sounds
>awful.


We are doing CANBUS on our newer stuff.  Using STM32s, NXP and TI
processors.  We have a couple guys working on most of the CAN
software. 

Expect it to take a while to get it right.  A single processor is
probably a bit easier though than multiples as long as your
requirements aren't too high.

At least the address filtering and such is done in hardware

boB

We prefer isolated CAN -- one less ground loop to debug.  We've used the ISO1050 for years, but it's not FD-compliant and doesn't regulate the voltage on the isolated side.  Also, the ISO1050 is out of stock everywhere, natch.  But isolating your CAN bus is something to consider.

On Sat, 14 Aug 2021 10:03:08 +0100, Michael Kellett <mk@mkesc.co.uk>
wrote:

>On 13/08/2021 16:25, jlarkin@highlandsniptechnology.com wrote:
>> A customer wants us to build a box (basically a cinder block bristling
>> with connectors) that includes a CAN bus for control. We'd include
>> ethernet too, for more general use.
>> 
>> Can someone recommend a good chip or chip set to do slow CAN? A good
>> eval kit or equivalent? A good way to make a PC talk CAN?
>> 
>> We'd have an internal uP, one of the ST Arm things.
>> 
>> 
>> 
>There are several possible CAN pitfalls, mainly to do with physical 
>interfaces and protocols.
>There is low speed fault tolerant CAN and the more common high speed not 
>fault tolerant CAN. There are ISO specs.
>Then there are protocols, like CANOpen - but there are zillions of them.
>
>The CAN peripheral on the ST chip will probably be OK for anything 
>hardware except CAN FD. I've known people get fussy about clock speeds 
>and want "exactly" the odd speed they are using which may not fit well 
>with the processor clock.
>
>If you need to write code to support some of the complex protocols it's 
>a lot of work.
>
>On the other hand if your customer has a sensible and documented home 
>brew protocol it can be quite simple and problem free.
>
>MK

I've been told that ST has software drivers for their CAN interfaces,
and like their ethernet stuff, it's pretty bad.

We are replacing some old boxes and the customer probably wants them
to be drop-on replacements for their old home-made stuff. That sounds
awful.



-- 

Father Brown's figure remained quite dark and still; 
but in that instant he had lost his head. His head was
always most valuable when he had lost it.



  

On 13/08/2021 16:25, jlarkin@highlandsniptechnology.com wrote:
> A customer wants us to build a box (basically a cinder block bristling
> with connectors) that includes a CAN bus for control. We'd include
> ethernet too, for more general use.
> 
> Can someone recommend a good chip or chip set to do slow CAN? A good
> eval kit or equivalent? A good way to make a PC talk CAN?
> 
> We'd have an internal uP, one of the ST Arm things.
> 
> 
> 
There are several possible CAN pitfalls, mainly to do with physical 
interfaces and protocols.
There is low speed fault tolerant CAN and the more common high speed not 
fault tolerant CAN. There are ISO specs.
Then there are protocols, like CANOpen - but there are zillions of them.

The CAN peripheral on the ST chip will probably be OK for anything 
hardware except CAN FD. I've known people get fussy about clock speeds 
and want "exactly" the odd speed they are using which may not fit well 
with the processor clock.

If you need to write code to support some of the complex protocols it's 
a lot of work.

On the other hand if your customer has a sensible and documented home 
brew protocol it can be quite simple and problem free.

MK

On Fri, 13 Aug 2021 09:12:40 -0700 (PDT), Ed Lee
<edward.ming.lee@gmail.com> wrote:

>On Friday, August 13, 2021 at 9:08:40 AM UTC-7, jla...@highlandsniptechnology.com wrote:
>> On Fri, 13 Aug 2021 08:47:21 -0700 (PDT), Ed Lee 
>> <edward....@gmail.com> wrote: 
>> 
>> >On Friday, August 13, 2021 at 8:25:37 AM UTC-7, jla...@highlandsniptechnology.com wrote: 
>> >> A customer wants us to build a box (basically a cinder block bristling 
>> >> with connectors) that includes a CAN bus for control. We'd include 
>> >> ethernet too, for more general use. 
>> >> 
>> >> Can someone recommend a good chip or chip set to do slow CAN? A good 
>> >> eval kit or equivalent? A good way to make a PC talk CAN? 
>> > 
>> >There are USB-CAN adapters available. 
>> > 
>> >> We'd have an internal uP, one of the ST Arm things. 
>> > 
>> >You probably already have CAN available on PA11 and PA12, but are shared with USB. 
>> >What is the exact STM model number?
>> It's an STM32F207IGT6. It does have two CAN interfaces. Do we just 
>> need a transceiver? Any suggestions?
>
>MCP2551

Yikes, there are tens of thousands available. I would have thought the
car chip crisis would have affected that. Maybe they go full-custom.

Thanks



-- 

Father Brown's figure remained quite dark and still; 
but in that instant he had lost his head. His head was
always most valuable when he had lost it.



  

fredag den 13. august 2021 kl. 18.08.40 UTC+2 skrev jla...@highlandsniptechnology.com:
> On Fri, 13 Aug 2021 08:47:21 -0700 (PDT), Ed Lee 
> <edward....@gmail.com> wrote: 
> 
> >On Friday, August 13, 2021 at 8:25:37 AM UTC-7, jla...@highlandsniptechnology.com wrote: 
> >> A customer wants us to build a box (basically a cinder block bristling 
> >> with connectors) that includes a CAN bus for control. We'd include 
> >> ethernet too, for more general use. 
> >> 
> >> Can someone recommend a good chip or chip set to do slow CAN? A good 
> >> eval kit or equivalent? A good way to make a PC talk CAN? 
> > 
> >There are USB-CAN adapters available. 
> > 
> >> We'd have an internal uP, one of the ST Arm things. 
> > 
> >You probably already have CAN available on PA11 and PA12, but are shared with USB. 
> >What is the exact STM model number?
> It's an STM32F207IGT6. It does have two CAN interfaces. Do we just 
> need a transceiver? Any suggestions?

yes you just need a transciever (and possibly a termination resistor)
something like a MCP2551 or one of the numerous similar all in SO8
They need 5V, you can get 3.3V transceivers but I seem to remember 
some claiming they are not fully compliant with the all of the CAN spec.
(though not in a way that I've seen matter)

On Friday, August 13, 2021 at 9:08:40 AM UTC-7, jla...@highlandsniptechnology.com wrote:
> On Fri, 13 Aug 2021 08:47:21 -0700 (PDT), Ed Lee 
> <edward....@gmail.com> wrote: 
> 
> >On Friday, August 13, 2021 at 8:25:37 AM UTC-7, jla...@highlandsniptechnology.com wrote: 
> >> A customer wants us to build a box (basically a cinder block bristling 
> >> with connectors) that includes a CAN bus for control. We'd include 
> >> ethernet too, for more general use. 
> >> 
> >> Can someone recommend a good chip or chip set to do slow CAN? A good 
> >> eval kit or equivalent? A good way to make a PC talk CAN? 
> > 
> >There are USB-CAN adapters available. 
> > 
> >> We'd have an internal uP, one of the ST Arm things. 
> > 
> >You probably already have CAN available on PA11 and PA12, but are shared with USB. 
> >What is the exact STM model number?
> It's an STM32F207IGT6. It does have two CAN interfaces. Do we just 
> need a transceiver? Any suggestions?

MCP2551

On Fri, 13 Aug 2021 08:47:21 -0700 (PDT), Ed Lee
<edward.ming.lee@gmail.com> wrote:

>On Friday, August 13, 2021 at 8:25:37 AM UTC-7, jla...@highlandsniptechnology.com wrote:
>> A customer wants us to build a box (basically a cinder block bristling 
>> with connectors) that includes a CAN bus for control. We'd include 
>> ethernet too, for more general use. 
>> 
>> Can someone recommend a good chip or chip set to do slow CAN? A good 
>> eval kit or equivalent? A good way to make a PC talk CAN? 
>
>There are USB-CAN adapters available.
>
>> We'd have an internal uP, one of the ST Arm things. 
>
>You probably already have CAN available on PA11 and PA12, but are shared with USB.
>What is the exact STM model number?

It's an STM32F207IGT6. It does have two CAN interfaces. Do we just
need a transceiver? Any suggestions?



-- 

Father Brown's figure remained quite dark and still; 
but in that instant he had lost his head. His head was
always most valuable when he had lost it.



  

On Friday, August 13, 2021 at 8:49:05 AM UTC-7, lang...@fonz.dk wrote:
> fredag den 13. august 2021 kl. 17.25.37 UTC+2 skrev jla...@highlandsniptechnology.com: 
> > A customer wants us to build a box (basically a cinder block bristling 
> > with connectors) that includes a CAN bus for control. We'd include 
> > ethernet too, for more general use. 
> > 
> > Can someone recommend a good chip or chip set to do slow CAN? A good 
> > eval kit or equivalent? A good way to make a PC talk CAN? 
> > 
> > We'd have an internal uP, one of the ST Arm things.
> many of the STMs have CAN all you need is a transciever 
> 
> many of them also have USB so that's an easy way to make a PC talk CAN

The low pin count versions probably have USB and CAN sharing pins.  But since he wants ETH, probably need a high pin count chip anyway.

fredag den 13. august 2021 kl. 17.25.37 UTC+2 skrev jla...@highlandsniptechnology.com:
> A customer wants us to build a box (basically a cinder block bristling 
> with connectors) that includes a CAN bus for control. We'd include 
> ethernet too, for more general use. 
> 
> Can someone recommend a good chip or chip set to do slow CAN? A good 
> eval kit or equivalent? A good way to make a PC talk CAN? 
> 
> We'd have an internal uP, one of the ST Arm things. 

many of the STMs have CAN all you need is a transciever

many of them also have USB so that's an easy way to  make a PC talk CAN