External HR sensor, HRM app and RAM

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dapgo
I want to use an external BLE HR sensor with the old bangle.js1 and during the process I am getting following impressions and doubts.

Firstly, I install "Bluetooth Heart Rate Monitor" and the feedback is
- Too high usage of memory for a bangle.js1, it remove almost everything to free enough memory, and even after that sometimes i got the "New interpreter error: CALLBACK,MEMORY"
- Setting: Modes
  - I miss a mode ONLY/exclusive for external sensor active or not (I assume that currently this option can be set with custom mode)
about the README:
For the "Custom" mode, options are not explained and it would be useful, specially for non native english speakers

About Memory/performance:
It seems that "Bluetooth Heart Rate Monitor" and its setting are using almost the complete bangle.js RAM.
What about the slow SPI flash?
Is it possible to reduce the usage of the limited and precious RAM without changing code?

I assume that a change of code that replaces vars by static values would reduce significantly the RAM usage, right?

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halemmerich in reply to @dapgo

You should get BT HRM only when selecting the custom mode and setting that to:

Replace HRM ✔️ (replacing the internal sensors values)
Start w. HRM ✔️ (react to the same power calls as the internal sensor)
HRM Fallback ☐ (do not try to activate the internal sensor if BT gets lost)

Moving the code that is able to detect and pair with sensors into the settings could probably reduce the RAM use by quite a bit with the cost of always having to pair a sensor before use. That is probably not really a problem, most devices I know actually need some configuration before using a HRM instead of using whatever is available.

Another possibility would be a low memory mode hard coding a lot more of the connection steps without the custom logic for handling many of the errors and parsing of additional data like battery and HRV data. Even restoring the initial implementation as base app and making the current one into a BT HRM+ version like many clocks are currently having would probably help a lot on B1.

The BTHRM widgets should be blue/dark blue for the "BT HR" recorder, green/dark green for the "HR int" internal recorder and no other colors should be possible. The normal "HRM" recorder (icon should be red) is enough if you set BTHRM to replace the HRM event.

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