rework sensor instantiation to saves memory by removing the static allocation by Links2004 · Pull Request #8054 · meshtastic/firmware

Links2004 · 2025-09-20T12:26:43Z

rework I2C sensor init.

The goal is to only instantiate sensors that are pressend to save memory.

Side effacts:

easier sensor integration (less C&P code, sensor only needs to be "registerd" at one place)
nodeTelemetrySensorsMap can be removed when all devices are migrated to save more RAM

🤝 Attestations

I have tested that my proposed changes behave as described.
I have tested that my proposed changes do not cause any obvious regressions on the following devices:
- Heltec (Lora32) V2.1
- Heltec (Lora32) V3
- LilyGo T-Deck
- LilyGo T-Beam
- RAK WisBlock 4631
- Seeed Studio T-1000E tracker card
- Other (please specify below)

Copilot

Pull Request Overview

This pull request replaces static allocation of the bsecState buffer with dynamic allocation using malloc() to save 238 bytes of static memory. The change moves the buffer allocation from a class member to local variables within the methods that use it.

Key Changes

Removed static bsecState array from BME680Sensor class member variables
Added dynamic allocation with malloc() in loadState() and updateState() methods
Added proper error handling and memory cleanup with free()

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
BME680Sensor.h	Removes static bsecState array declaration from class members
BME680Sensor.cpp	Implements dynamic allocation with malloc/free in loadState() and updateState() methods

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mverch67 · 2025-09-20T19:18:51Z

A much larger portion of static allocation could be saved if all the sensor instances are declared as pointer and allocated in heap space during init. Then no changes in this BSEC sensor class are required, e.g. see here:

firmware/src/modules/Telemetry/EnvironmentTelemetry.cpp

Line 72 in b49496d

BME680Sensor bme680Sensor;

Links2004 · 2025-09-20T20:13:17Z

true, had a look at EnvironmentTelemetry.cpp and it looks like there is a lot more possibility for optimizion.
In my opinion there is a loot to gain there, the current desigen looks very inefficient over all.

looked a bit deeper and I think the I2C device handling overall needs some work.

Links2004 · 2025-09-21T09:57:02Z

have working code that elimenates the need for nodeTelemetrySensorsMap and only creates the sensor instances when the I2C scan found a device.

moved over 4 sensors to show case the idea, but want some feedback before doing all of them.
moving this 4 sensors over saved already 1152 bytes of static allocations.

I dont see that we get memory fragmentation problem with this code, since the only cases where we delete / free something is when the sensor failed it initialisation.

tested this with a BMP-280 connected to a Heltec V2.1

please review and give feedback if this code is something that can be merged (will migrate the other sensors then).

the goal is to only instantiate sensors that are pressend to save memory. side effacts: - easyer sensor integration (less C&P code) - nodeTelemetrySensorsMap can be removed when all devices are migrated

RAM -816 Flash -916

Links2004 · 2025-09-26T18:59:01Z

did a second batch of sensors

RAM -816
Flash -916

RAM -192 Flash -60

Flash -112

not sure what magic is used but it works

thebentern · 2025-09-27T10:37:32Z

Tagging @oscgonfer for visibility

Links2004 · 2025-09-27T10:48:53Z

The PR now covers all sensors that where allocated staticly in EnvironmentTelemetry.

Total saved:

RAM -2160
Flash -4332

we will save CPU cycles too since we do a lot less hasSensor calls.

some sensors like the INA ones are part of PowerTelemetry and EnvironmentTelemetry not sure why but I did not touch them.

Ready for review.

Copilot

Pull Request Overview

Copilot reviewed 63 out of 63 changed files in this pull request and generated 5 comments.

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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

…ic#8054. Fixes segfault on native.

…location (meshtastic#8054) * rework I2C sensor init the goal is to only instantiate sensors that are pressend to save memory. side effacts: - easyer sensor integration (less C&P code) - nodeTelemetrySensorsMap can be removed when all devices are migrated * add missing ifdef * refactor a bunch of more sensors RAM -816 Flash -916 * fix build for t1000 * refactor more sensors RAM -192 Flash -60 * improve error handling Flash -112 * fix build * fix build * fix IndicatorSensor * fix tracker-t1000-e build not sure what magic is used but it works * Apply suggestion from @Copilot Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Apply suggestion from @Copilot Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Apply suggestion from @Copilot Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Update src/modules/Telemetry/Sensor/DFRobotGravitySensor.h Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Fix --------- Co-authored-by: Ben Meadors <benmmeadors@gmail.com> Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

thebentern requested review from caveman99 and Copilot and removed request for caveman99 September 20, 2025 12:31

Copilot AI reviewed Sep 20, 2025

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Comment thread src/modules/Telemetry/Sensor/BME680Sensor.cpp Outdated

Comment thread src/modules/Telemetry/Sensor/BME680Sensor.cpp Outdated

thebentern added the enhancement New feature or request label Sep 20, 2025

Links2004 marked this pull request as draft September 20, 2025 20:13

Links2004 changed the title ~~use malloc for bsecState - saves 238 byte of static allocation~~ [WIP] rework sensor allocation to saves all the static allocation Sep 21, 2025

Links2004 force-pushed the save_memory_bme680 branch from 1fe2139 to 16bdf14 Compare September 21, 2025 09:54

Links2004 marked this pull request as ready for review September 21, 2025 09:57

Links2004 changed the title ~~[WIP] rework sensor allocation to saves all the static allocation~~ [WIP][needs feedback] rework sensor allocation to saves all the static allocation Sep 21, 2025

rework I2C sensor init

3bb927e

the goal is to only instantiate sensors that are pressend to save memory. side effacts: - easyer sensor integration (less C&P code) - nodeTelemetrySensorsMap can be removed when all devices are migrated

Links2004 force-pushed the save_memory_bme680 branch from 16bdf14 to 3bb927e Compare September 21, 2025 10:05

add missing ifdef

5e7cb4c

Links2004 mentioned this pull request Sep 21, 2025

NimbleBLE update to 2.3.6 #7880

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Links2004 changed the title ~~[WIP][needs feedback] rework sensor allocation to saves all the static allocation~~ [WIP][needs feedback] rework sensor instantiation to saves memory by removing the static allocation Sep 21, 2025

jp-bennett requested a review from fifieldt September 21, 2025 17:57

Links2004 and others added 2 commits September 26, 2025 19:55

Merge branch 'develop' into save_memory_bme680

48a07d9

refactor a bunch of more sensors

113ce64

RAM -816 Flash -916

fix build for t1000

4844c81

Links2004 changed the title ~~[WIP][needs feedback] rework sensor instantiation to saves memory by removing the static allocation~~ rework sensor instantiation to saves memory by removing the static allocation Sep 27, 2025

Links2004 and others added 5 commits September 27, 2025 10:44

refactor more sensors

a673b76

RAM -192 Flash -60

improve error handling

2bf6b1f

Flash -112

fix build

2d55000

fix build

5e85a14

Merge branch 'develop' into save_memory_bme680

1ab1e1d

Links2004 added 2 commits September 27, 2025 12:07

fix IndicatorSensor

d1faa83

fix tracker-t1000-e build

3fa84eb

not sure what magic is used but it works

thebentern and others added 4 commits October 1, 2025 19:33

Merge branch 'develop' into save_memory_bme680

f08931b

Merge branch 'develop' into save_memory_bme680

de4ccf6

Merge branch 'develop' into save_memory_bme680

dd788e2

Merge branch 'develop' into save_memory_bme680

9647e3f

thebentern requested a review from Copilot October 12, 2025 12:43

Copilot AI reviewed Oct 12, 2025

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thebentern and others added 8 commits October 12, 2025 08:37

Merge branch 'develop' into save_memory_bme680

c22e304

Apply suggestion from @Copilot

5f65ec6

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Apply suggestion from @Copilot

a94f867

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Apply suggestion from @Copilot

45d767c

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Update src/modules/Telemetry/Sensor/DFRobotGravitySensor.h

012c6e9

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Fix

a02dba8

Merge branch 'develop' into save_memory_bme680

8f3f7b5

Merge branch 'develop' into save_memory_bme680

0d11bcc

thebentern approved these changes Oct 13, 2025

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thebentern merged commit a71b47b into meshtastic:develop Oct 13, 2025
76 checks passed

Mictronics added a commit to Mictronics/meshtastic_firmware that referenced this pull request Nov 1, 2025

Fix use after free for i2cscanner pointer introduced with PR meshtast…

d200d30

…ic#8054. Fixes segfault on native.

oscgonfer mentioned this pull request Jan 9, 2026

Changing how sensor map is created in nodeTelemetrySensorsMap fablabbcn/smartcitizen-meshtastic#9

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mverch67 commented Sep 20, 2025

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Links2004 commented Sep 20, 2025 •

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