Hi Fuxin,
- First here are steps to get started with External mode:
First make sure to have the latest version of the Embedded Coder Support Package for Texas Instruments C2000 Processors as we made recent changes to our External mode implementation.
Now let's speed things up :-)
- Cranking External mode:
External mode uses SCIA to communicate between the host and the target and will use the baudrate that you have set in your configuration parameters. For better experience with External mode, make sure to increase the baudrate for SCIA.
If using a recent controlCard or Launchpad, the serial over USB chip (FTDI FT2332H family) can accept any baudrates up to 6 Mbps or exactly 9 Mbps or exactly 12 Mbps.
If using a older controlCard or docking station, the serial over USB chip (FTDI FT2332D family) can accept any baudrates up to 1.5 Mbps or exactly 2 Mbps or exactly 3 Mbps.
If using the F28027 LaunchPad, you can go up to 3.75Mbps which is the max that the processor can do.
By doing this you can log signals up to ~5kHz after which you may experience gaps in your logged data.
- Buffered External mode
Monitoring buffers at a slower rate allows you to run External mode simulations and watch signals at higher rates. I recently posted an example on how to do this on the F28379D Launchpad. The same technique can be applied with the F28027 Launchpad. I was able to watch signals at 20kHz with this technique on the F28379D Launchpad. This requires more memory on the target, you may have to increase the heap size to be able to run External mode. Look at the models I provided on this page, in the configuration parameters of the model, under "code generation", I selected "specify" for the "Build configuration", and in the linker string, I changed the "--heap_size" from the default value.
- 2-model approach
This is the fastest way to log data in realtime, as you can specify your own light weight protocol. The idea is to create 2 models, one that runs on the target and sends data to serial. the second one that runs on the host and gets data from the target. I show a full example running a DC/DC buck converter demo where I log 2 uint16 signals at 200kHz with this technique. Watch the video on the page for full details of how to implement this technique. I'm using the F28377S Launchpad in this demo, but the same technique can be applied on the F28027 Launchpad.
I hope it helps,
Thanks,
Antonin.
