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[hmc5883l] Fix wrong gain for 88uT range#14281

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swoboda1337 merged 1 commit intoesphome:devfrom
swoboda1337:fix-hmc5883l-88ut-gain
Feb 25, 2026
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[hmc5883l] Fix wrong gain for 88uT range#14281
swoboda1337 merged 1 commit intoesphome:devfrom
swoboda1337:fix-hmc5883l-88ut-gain

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@swoboda1337 swoboda1337 commented Feb 25, 2026

What does this implement/fix?

Fix incorrect gain value for the 88µT range. The code had 0.073 mG/bit instead of 0.73 mG/bit, causing readings to be 10x too low.

The datasheet (page 14) specifies a gain of 1370 LSb/Gauss for this range: 1000 / 1370 = 0.73 mG/bit. All other ranges were correct.

Types of changes

  • Bugfix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • Developer breaking change (an API change that could break external components)
  • Code quality improvements to existing code or addition of tests
  • Other

Related issue or feature (if applicable):

Pull request in esphome-docs with documentation (if applicable):

N/A

Test Environment

  • ESP32
  • ESP32 IDF
  • ESP8266
  • RP2040
  • BK72xx
  • RTL87xx
  • LN882x
  • nRF52840

Example entry for config.yaml:

sensor:
  - platform: hmc5883l
    address: 0x1E
    field_strength_x:
      name: "HMC5883L Field Strength X"
    field_strength_y:
      name: "HMC5883L Field Strength Y"
    field_strength_z:
      name: "HMC5883L Field Strength Z"
    heading:
      name: "HMC5883L Heading"
    range: 88uT
    update_interval: 1s

Checklist:

  • The code change is tested and works locally.
  • Tests have been added to verify that the new code works (under tests/ folder).

@swoboda1337
[hmc5883l] Fix wrong gain for 88uT range
519ff1d 
The 88uT range gain was 0.073 mG/bit instead of 0.73 mG/bit,
causing readings to be 10x too low. The datasheet specifies
1370 LSb/Gauss for this range, giving 1000/1370 = 0.73 mG/bit.

Fixes esphome#14276

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot AI review requested due to automatic review settings February 25, 2026 17:40
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github-actions bot commented Feb 25, 2026

To use the changes from this PR as an external component, add the following to your ESPHome configuration YAML file:

external_components:
  - source: github://pr#14281
    components: [hmc5883l]
    refresh: 1h

(Added by the PR bot)

@swoboda1337 swoboda1337 added this to the 2026.2.2 milestone Feb 25, 2026
Copilot AI reviewed Feb 25, 2026
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Pull request overview

Fixes incorrect field strength scaling for the HMC5883L 88µT range so reported magnetic field values are no longer 10× too low.

Changes:

  • Corrected the gain constant for HMC5883L_RANGE_88_UT from 0.073f to 0.73f (mG/bit), aligning with the datasheet’s 1370 LSB/Gauss value.

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codecov-commenter commented Feb 25, 2026

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.28%. Comparing base (ede8235) to head (519ff1d).

Additional details and impacted files 
@@            Coverage Diff             @@
##              dev   #14281      +/-   ##
==========================================
+ Coverage   74.25%   74.28%   +0.02%     
==========================================
  Files          55       55              
  Lines       11595    11595              
  Branches     1583     1583              
==========================================
+ Hits         8610     8613       +3     
+ Misses       2580     2578       -2     
+ Partials      405      404       -1

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

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  • ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

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github-actions bot commented Feb 25, 2026

Memory Impact Analysis

Components: hmc5883l
Platform: esp8266-ard

Metric Target Branch This PR Change
RAM 28,944 bytes 28,944 bytes ➡️ +0 bytes (0.00%)
Flash 287,431 bytes 287,431 bytes ➡️ +0 bytes (0.00%)

Note: This analysis measures static RAM and Flash usage only (compile-time allocation).
Dynamic memory (heap) cannot be measured automatically.
⚠️ You must test this PR on a real device to measure free heap and ensure no runtime memory issues.

This analysis runs automatically when components change. Memory usage is measured from a representative test configuration.

@swoboda1337 swoboda1337 merged commit 5dffced into esphome:dev Feb 25, 2026
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swoboda1337 commented Feb 25, 2026

Thanks

jesserockz pushed a commit that referenced this pull request Feb 26, 2026
@swoboda1337 @jesserockz
[hmc5883l] Fix wrong gain for 88uT range (#14281)
5a1d642 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@jesserockz jesserockz mentioned this pull request Feb 26, 2026
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HMC5883L sensor wrong readings on 88uT range

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