[Oberon] LED in FPGA Oberon

[Walter Gallegos]

Hi Wojtek,

LED even practical into PO ecosystem is hardware specific. In my 
RiscCore there are not LEDs connected to processor core. This 
functionality is relayed to the custom project. The final user implement 
your own status indicators in hardware and the correspondent software 
module; so, LED related lines are commented in my compiler files set to 
avoid mistakes.

Regards.

El 5/11/18 a las 23:36, Skulski, Wojciech escribió:
> Hello:
>
> There is this "proper procedure" named LED on page 15 in the Oberon-07 Report dated Revision 1.10.2013 / 3.5.2016, which is the newest version of the language.
>
> Proper procedures:
> Name Argument types Function
> LED(n) INTEGER display n on LEDs
>
> It is a very convenient procedure indeed. It is provided in both the Oberon System proper, as well as Astrobe. It is used in the core bootloader to track the progression of the code.
>
> However... Is it not strange that the little debugging utility geared towards just the FPGA applications has been carved into the Language Report? I would rather see it as a SYSTEM feature SYSTEM.LED(n), or as an "undocumented feature" of a particular implementation. Ideally, it would have been a separate MODULE. But I do understand that it was needed for the bootloader which is executed prior to loading the system kernel. In this situation, SYSTEM.LED would be the most appropriate, IMHO.
>
> In my RiskFive we are not providing the FPGA pins to drive LEDS due to shortage of pins in the Artix-7 in the CSG324 package. I am rather providing an I2C pin expander with eight LEDs. We will provide for eight LEDs driven with outputting an INTEGER to a particular address, where the I2C firmware will take care of sequencing the signals. So I am not ditching the LEDs. But I do not like including such a specialized facility directly in the Language Report.
>
> Wojtek
> --
> Oberon at lists.inf.ethz.ch mailing list for ETH Oberon and related systems
> https://lists.inf.ethz.ch/mailman/listinfo/oberon
>