CAN bus ?

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Feb 5, 2021, 3:42:11 PM2/5/21
to Annex WiFi RDS
Civilisation has become dependent on the reliable connectivity of CAN bus in every area of travel and industry. And with all the benefits that CAN offers, it's not so surprising there is a lot of interest in arduino CAN projects... whether for data sniffing via the OBD2 port, or directly connecting onto a vehicles CAN bus to add sensors and relays etc, or simply for linking arduinos and their peripherals in hobby projects.

The arduino sketch is usually just a loop to keep reading or writing CAN data packets, while the CAN library (typically for MCP2515) handles the low-level driver interactions which provide the fault-tolerance and reliability. Any additional 'smarts' for data filtering/parsing etc is usually via serial to a high level computer program.

if Annex had CAN capability it could do so much better... offering  benefits of a convenient wireless browser interface, plus rapid development, and probably already have enough 'smarts' to be a self-sufficient data sniffer/filter/parser/controller etc (perhaps an intelligent Annex32 SD data-logger).

So might Annex (or perhaps just Annex32 which already has ESP32 CAN capability) eventually have ability to stop arduino's from having all the CAN fun ?


Feb 7, 2021, 3:48:06 AM2/7/21
to Annex WiFi RDS
Hi Robin,
I'm experimenting the support for the CAN bus for the ESP32 with some positive results.
I'll probably include its support for next releases even if I fear that the interest will be very limited and mainly oriented toward the professional world that goes beyond the scope of the Annex license.


Feb 7, 2021, 2:06:36 PM2/7/21
to Annex WiFi RDS
Very good news Francesco… what CAN modules should I order ?

Even at 1Mbs the CAN bus can be up to 40m long, so at 500Kbs (the norm) it should be capable of even greater distances while still achieving CAN fault-tolerance and reliability. Another CAN benefit is that it uses software identifiers instead of hardware addressing, thereby making dynamic addressing  possible - offering ability for backups of crucial devices to co-exist on the bus ready to dynamically step in to take over important functionality in event of primary device failure.
So my main interest is for linking several clusters of interactive Annex devices and their analog and digital peripherals into a reliable autonomous automation and control system, with only a single wifi connection for remote monitoring and control.  Will be especially useful for analog devices which are limited by the number of ADC's to be scanned and how often to scan them - which is ok for a 2 servo pan & tilt cctv platform, but not practical for (eg:) a sensor glove to control a robotic hand... whereas CAN bus could allow multiple devices to share the analog load, all reliably interconnected.

But I can also predict many interesting uses for Annex CAN in my camper conversion, eg: remote monitoring of battery voltage and inside and outside temps, controlling lighting and central locking and dash music from the rear, adding new CAN-controlled internal lighting and other devices.
WiIl all be much more fun using Annex than if having to use arduino.

Here's some youtube CAN links if anyone is interested…

Good CAN description, even though 5 years old
More recent overview
Sending and receiving digital and analog info between arduinos
Hack your Car series
Some CAN eye-openers
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