fpp-to-xml unable to compile telemetry limits with boolean types

[kubiak-jpl]

F´ Version	v3.4.3
Affected Component	fpp-to-xml

---

Problem Description

Unable to use telemetry limits with boolean types. The fpp-to-xml script is unable to generate an XML file. Here is an example built from the Ref deployment

Version 1:

telemetry test2: bool id 7 \
low { \
  orange false \
}

fpp-to-xml
/Users/kubiak/Documents/fprime/Ref/SignalGen/Telemetry.fppi:26.10
  orange false \
         ^
  included at /Users/kubiak/Documents/fprime/Ref/SignalGen/SignalGen.fpp:69.13
error: cannot convert bool to a numeric type

Version 2:

telemetry test2: bool id 7 \
low { \
  orange 0 \
}

fpp-to-xml
/Users/kubiak/Documents/fprime/Ref/SignalGen/Telemetry.fppi:26.10
  orange 0 \
         ^
  included at /Users/kubiak/Documents/fprime/Ref/SignalGen/SignalGen.fpp:69.13
error: cannot convert Integer to bool

Context / Environment

Execute fprime-util version-check and share the output.

Operating System: Darwin
CPU Architecture: arm64
Platform: macOS-14.4.1-arm64-arm-64bit
Python version: 3.12.2
CMake version: 3.27.4
Pip version: 24.0
[WARNING] Cannot import 'pkg_resources'. Will not check tool versions.

Also observed on

Operating System: Linux
CPU Architecture: aarch64
Platform: Linux-6.5.0-26-generic-aarch64-with-glibc2.35
Python version: 3.10.12
CMake version: 3.22.1
Pip version: 22.0.2
Pip packages:
    fprime-tools==3.4.4
    fprime-gds==3.4.3
    fprime-fpp-*==2.1.0a5

How to Reproduce

1. Add the following line to SignalGen.fpp

telemetry test2: bool id 7 \
low { \
  orange false \
}

fpp-to-xml
/Users/kubiak/Documents/fprime/Ref/SignalGen/Telemetry.fppi:26.10
  orange false \
         ^
  included at /Users/kubiak/Documents/fprime/Ref/SignalGen/SignalGen.fpp:69.13
error: cannot convert bool to a numeric type

2. Rebuild the Ref deployment. Observe the following error

Expected Behavior

Expect to be able to use telemetry limits with Boolean telemetry types

[bocchino]

This isn't a bug; it's in the language specification. Limits are for numeric types only. In particular, it is not clear what a low or high limit should mean for a Boolean value. Boolean values are not ordered. Consider switching the output to a numeric type if you want to define limits for it.

[kubiak-jpl]

Maybe this a feature request then. I do think there would be value in telemetry limits for non-numeric types. I don't think of these as numeric limits so much as warnings to the GDS user that a telemetry value requires attention. In that sense it would make sense for boolean and enumeration channels to have channel limits.

[bocchino]

Sure, we could add the feature of specifying red, orange, and yellow values (as opposed to limits) for any telemetry channel type. Can you open a discussion topic on this, to get input from others? Then we can close this issue.