Flowcode Support Board

At the moment I have a simple program using 1 of the DACs on ESP32 Devkit C, different values running in a continuous loop.
The problem is a momentary delay every 4 or so seconds, which appears to occur at the same time TX0 transmits data.
Is there away to disable or workaround this? Thanks
Attached

It's probably the watch-dog timer triggering an error - which will output a message to the UART (try connecting using PUTTY or similar to check this)

Try FeedTheDog - see viewtopic.php?p=4447#p4447

This is happening because the esp32 is running a multi-tasking operating system (RTOS) and expects tasks to cooperate by yielding to allow other tasks to run.

A better way to do this might be too move the output to a timer
Interrupt running every 4ms.

Martin

Thank you Martin.
As you mentioned WDT is triggered. I have a lot to add, but wanted to test the DAC first.
However I do this I need to keep the DAC step a constant rate.

Brian

Hi Brian,

Output to the DAC in a timer interrupt (running every 4ms in the example) - the accuracy is very good (remarkably good) - just output the next value and return (no delay) - try using an array of values and increment the index to this on each interrupt - use the mod (%) operator to loop.

Martin

As a simple example.

Note I output 12 values (I think this is how many your sample had - but the number can be varied to suit) - and I just output the values 1..12 (too lazy to copy your data)
As an aside - this demonstrates an issue with simulation. Simulate the program (debug-run) at a fast rate (say 10Hz) and FC becomes unresponsive as it tries to display the steps from the timer interrupt. It looks like it is running the interrupt at a simulated 'rate' that is faster that the display update - and this is 'buffered' - so that clicking on any control (stop, pause, change speed etc) - takes a long time for the command to reach the top of the message queue? Or it might be that the interrupt is taking longer than the 4ms (simulated) time - (it tries to update the 2d display) and the interrupt isn't blocked when simulating?

Martin

Thank you for the example. Much appreciated.

Brian

Hi Brian,

No problem.
I've just got it up and running on hardware - and seems to run AOK. With a couple of issues - mainly it won't work under v5 (lots of 'timer not defined errors) - if you are using the (recommended) v4 no problems.
You'll also need to call 'Enable' on the DAC channel.
The DAC only allows 8 bit resolution (in the component) - I'm not sure if it should allow 12 bits?

Martin

Hi Martin,
Got it running from the example, thanks again. I had already enabled the DAC. I recalled from previous Flowcode versions, the simulation was quite sympathetic and would run without it!
8 bits is fine for my application. Previously used 16F886 with SPI DAC (MCP4921).

Brian