Using Lattepanda v1 (Arduino Leonardo ATMega32U4 µC) as pure SPI Slave

[Se3ri0us]

Hi guys,
is there a possibility to operate the Arduino Leonardo (ATMega32U4) via Telemetrix4Arduino (Telemetrix in Python is used) also as a pure slave? So it should only receive data from another master. My master is a FT232H from FTDI.
I went through the Examples and didn't find any possibility so far. The ATMega32U4 can be used as a pure slave according to the datasheet. The maximum SPI clock should be fClk/4, at 16MHz this results in 4MHz.

Thanks in advance!

[MrYsLab]

Thanks for the question. The suggestion is an excellent one but, unfortunately, would not work with the design of Telemetrix4Arduino. Even though the sketch appears to work asynchronously, that is, reporting events as they seem to happen, it is implemented synchronously by polling for data changes.

Supporting the SPI interface as an SPI peripheral would require enabling interrupts. An interrupt can occur at anytime and may interfere with other active interfaces by blocking at a critical moment. For example, the HC-SR04 needs to time its pulses accurately. Receiving an interrupt could disrupt its timing cycle.

Again, thanks for the suggestion, but it is not practical for me to implement.

[Se3ri0us]

Thanks for the quick feedback! While analyzing the source code a bit I also noticed that no interrupts are used. Then it became clear to me that the concept is based on polling without interrupts. Since interrupts are needed for the SPI slave, as you said, this extension cannot be implemented. I understand that completely.
Do you know of any other Arduino - Python implementation that provides the SPI slave with interrupts?
If there is nothing there, I guess I will have to implement this myself.
Thanks again!

[MrYsLab]

I found this article, and it may help. It assumes that Python is being run on a Linux machine.

[Se3ri0us]

Thank you very much! That should make things easier. If I understand the slave code correctly, no interrupt is used here, only the SPI interrupt flag is queried and then the data is fetched.