Support question, possible to implement master on embedded system, i.e. not on Linux

[wolfc01]

Hi,

I have a question, what are the steps to perform to run the CANopen master on an embedded CPU (STM32 in my case). Is that easily feasible: has somebody realized that before?

We have 4 STM32 based processor boards of which one should act as the CANopen master node. We have requirements on having LSS, futher some low speed request responses between the master and slave nodes (all initiated by the master), without any realtime or throughput requirements. Further the required messages sized are small (<= 8 bytes) .

Br
Carl.

[robincornelius]

Hi, I don't use the LSS features but i'm always using one of my embedded nodes as a master, when used with my own nodes and other 3rd party can nodes. Think i've been up to about 30 nodes on the biggest systems. In the simplest terms to get it to work every time the process i always follow is :- 1. Set all slave nodes to start in pre-operational mode, and save this to their eeprom or how ever you set them up 2. Switch on the system. in the master node you may need a delay here to allow time for every slave to boot 3. From the master send a NMT_CommunicationsReset() (you may need to be careful you don't catch this signal on the master as well and reset yourself!) 4. Have a small delay to allow all nodes to reset. 5. Send a NMT_Start() to all nodes This procedure will ensure all PDOs are only sent when the NMT_Start is issued so everything is synchronized at start up. The above is very simple to be implemented on embedded system, just ensure the master bit on object 0x1F80 is set in the object dictionary and if using the EDS editor this will ensure the NMT_MASTER functions are available to send the communications reset/start bus etc,. Failing to do the CommunicationsReset will result in possibly unpleasant error messages related to Bus Off / TX Passive so if you also monitor emergency messages, this is a signal to clear everything after the typically unclean cold boot where there is always one node who sees a passive bus as they won the power on race first. There are a number of other choices for the startup where you may wish to ping each node via SDO to ensure its alive before issuing the NMT_Start() or you may wish to start certain nodes before others, but if you do this be very careful of who is sending and listening to PDOs as you could miss the initial messages which may or may not affect your system. LSS is just an earlier stage in the boot sequence, but i've never even tried to use that bit so can offer no advice on that. Robin

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On Wed, 3 Feb 2021 at 18:59, Carl ***@***.***> wrote: Hi, I have a question, what are the steps to perform to run the CANopen master on an embedded CPU (STM32 in my case). Is that easily feasible: has somebody realized that before? We have 4 STM32 based processor boards of which one should act as the CANopen master node. We have requirements on having LSS, futher some low speed request responses between the master and slave nodes (all initiated by the master), without any realtime or throughput requirements. Further the required messages sized are small (<= 8 bytes) . Br Carl. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#264>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABG2GGJRP5DOPU5CNSFQM3S5GJKVANCNFSM4XBKK6QA> .

[wolfc01]

Hi Robin,

thanks for your valuable input,

Br
Carl

[CANopenNode]

There is 309/CO_gateway_ascii, which should work on microcontroller with ascii interface. This could be used for rich service access with LSS, NMT, SDO, etc., as described in gettingStarted.md or LSSusage.md.

Othervise modules can be used separately LSS master, NMT master (quite simple) or SDO master (old example for blocking usage is here: https://github.com/CANopenNode/CANopenSocket/blob/7b8b45fcd2e2d6fa5a9a55d8f3aa8b54ce81a98b/canopend/src/CO_master.c)