[Solved] Reset a variable at fixed frequency

[Myzhar]

Hi all,

I have a data streaming firmware and to keep the stream alive I must reset a counter before it reaches a fixed value.

Is there a way to perform this operation with CubeMonitor while monitoring other values?

Thank you

Walter

[Thierry]

Hi Walter,

Yes it should be possible since your know the counter address.

Indeed as STM32CubeMonitor is able to read but also write some values at various addresses, then you can implement a logic in your flow that reset your counter when a condition is reached.

[Myzhar]

I think that I could use the "trigger" function, but I do not know how to use it

[Thierry]

Not sure the trigger can fit your needs. Could you please explain a bit more what you want to achieve and share your current flow such so that we can better help you ?

[Myzhar]

The FW works in this way:

1) The host sends the "Start data acquisition" command over USB and that sets a variable to 1 to indicate that the stream is started

2) During the data acquisition the host must send a ping before 6 seconds to avoid that the stream stops, the ping resets a counter that is increased at 400Hz

I must simulate this behavior:

1) set the "start stream" variable to 1

2) reset the counter to zero before it reaches the value 2400

The shared flows does exactly what I said, but I must continuously press the "Write" button on the dashboard to keep the stream alive

[Thierry]

Thanks will have a look and keep you informed.

[Thierry]

I have few questions / clarification on your current flow/logic :

1. starting the stream is done by setting sensStreamStatus.stream_status to 1. Correct ?
2. you need to reset the counter be setting systemStatus.data_sample_not_pinged_count to 1 (or 0??) every 6 seconds. Correct ?
3. do you really want to be able to write sensStreamStatus.stream_status & systemStatus.data_sample_not_pinged_count from the dashboard write widget or is it fine to do it only from the flow editor interface ?

[Myzhar]

1. correct
2. correct. Usually the host sends a ping every 1 second to reset `systemStatus.data_sample_not_pinged_count` to zero
3. I do not need the dashboard. I only added it because it's the only way that I not to set the variables

I'm really new to nodered. Is there a good documentation to read about it that is helpful to better understand Stm32CubeMonitor?

Thank you again for your help

Walter

[Thierry · Accepted solution]

Thanks your your answer. I have modified your flow accordingly, please find attached flow.

Here are the updates done in the flow :

• The main update concerns the way the data_sample_not_pinged_count & stream_status are written. Instead of using a write panel, I use 2 template nodes which forces the values for these 2 variables from the flow editor. These 2 template nodes are triggered by :
  • the start button for stream_status.
  • an inject node which is resetting data_sample_not_pinged_count every 1 second.
  • Detailed explanations on how to write values programatically are provided in this thread :https://community.st.com/s/question/0D53W000000ayg1SAA/hello-how-is-it-possible-to-change-a-variable-by-pressing-a-buttoni-just-can-change-a-variable-by-using-the-write-panel-butregards.
• Then I remove some useless nodes (write node, variable node that were used to write the data_sample_not_pinged_count & stream_status variables)
• Finally I also remove one useless switch node, as you can have several rules inside a single switch.

There are plenty of good document to read. The first one is the STM32CubeMonitor wiki available at

https://wiki.st.com/stm32mcu/wiki/STM32CubeMonitor:STM32CubeMonitor_overview. It is updated on regular basis with questions/answer coming from the this forum.

If you want more explanation on node-red framework, there is the node-red website which provides plenty of information from beginner to expert : https://nodered.org/docs/

Hope it answers your question

[Myzhar]

Thank you @Thierry​ 

it works as expected =)