Programming the eTPU itself can be complicated at times, or at least has something of a learning curve. The match and capture registers that are part of the ERA/ERB register sets are not directly accessible. To set a match register, the value must first go in an ERTA/ERTB register, and then an instruction issued to move the ERTA and/or ERTB register value into match register(s). The match registers can only be read by issuing an instruction that transfers their contents to the accessible ERTA/ERTB registers (rarely needed). Similarly, the capture registers can only be “read” by having their values transferred into ERTA/ERTB (done automatically at start of an execution thread, accomplished by writing the CHAN register otherwise).
Using the reference manual to learn how to program the eTPU is challenging. There is a book available that is more helpful – see https://www.ashware.com/etpu-programming-made-easy-book. Paired with the book are a series of labs/examples that can be downloaded and installed from http://services.ashware.com/Download_Files/eTpuBook.exe. Without the context of the book, these labs/examples would be difficult to work with, but perhaps would offer some value. They require the ASH WARE tools – free demo version available at https://www.ashware.com/Demos.
There is also direct training available for the eTPU, the next scheduled is in September, see https://www.ashware.com/etpu-training.
Another resource (mostly miscellaneous info) is https://etpu.org/.
John Diener
