drivers/sensors: Add AS5047D magnetic encoder driver

[DheerajSingh1107]

Summary

This PR adds a new SPI-based magnetic encoder driver for the AMS AS5047D.

The AS5047D is a 14-bit on-axis magnetic rotary encoder that communicates over SPI and is commonly used in motor control and robotics applications requiring precise angular position feedback.

This driver provides:

• 14-bit angular position readout (0–16383)
• SPI communication interface compatible with NuttX SPI framework
• Basic error detection using status bits from the device

The implementation follows existing NuttX sensor driver patterns and is designed to be reusable across supported boards.

Impact

• New Feature: Adds support for AS5047D encoder
• No breaking changes: Existing drivers and subsystems are unaffected
• Hardware: Requires an SPI interface (tested on STM32F4 SPI3)
• Build: Adds a new driver option (must be enabled via config)
• Use case: Motor control, robotics, FOC systems requiring precise angle feedback

No impact on existing APIs or backward compatibility.

Testing

Tested on:

• Board: STM32F446re (SPI3)
• Setup: AS5047D connected via SPI with proper CS handling

Test Procedure:

1. Initialized SPI bus and driver in NuttX

2. Performed continuous angle reads

3. Verified:

   • Stable 14-bit output range (0–16383)
   • No constant or stuck values
   • Correct response to shaft rotation

4. Checked error flags in returned data
   Observations:

• Angle values update correctly with rotation
• No communication faults observed under normal operation
• Timing adjustments were required for stable SPI reads
  Logs (example):

[acassis]

@DheerajSingh1107 thank you for your contribution, please align the CMakelist:

if(CONFIG_SENSORS_AS5047D)
  list(APPEND SRCS as5047d.c)
endif()

[linguini1]

Please add documentation for this driver :)

[acassis]

@DheerajSingh1107 please take a look at this PR I submitted to MT6816 (#18807) and add a board config to some board you are using with it and Documentation to your AS5047D, this way a new user will be able to get it working easily

[DheerajSingh1107]

Hi @linguini1 , does you mean add a description to as5047d.h header file or a rst file ?

[jerpelea]

please remove the merge commit

[linguini1]

Hi @linguini1 , does you mean add a description to as5047d.h header file or a rst file ?

Some RST docs please!

[acassis]

please remove the merge commit

I think it is guilt of our Documentation:
https://nuttx.apache.org/docs/latest/contributing/making-changes.html

I fixed it at "Submitting Your Changes to NuttX" but I didn't modified the original documentation that shows how to setup the environment.

[DheerajSingh1107]

@DheerajSingh1107 please take a look at this PR I submitted to MT6816 (#18807) and add a board config to some board you are using with it and Documentation to your AS5047D, this way a new user will be able to get it working easily

Thanks

[jerpelea]

please remove the merge commit

[acassis]

@DheerajSingh1107 seems like there is some issue with the CMakefile:

ERROR __main__.py:618: Check failed: /home/runner/work/nuttx/nuttx/nuttx/drivers/sensors/CMakeLists.txt

cmake-format check failed, run following command to update the style:
  $ cmake-format <src> -o <dst>

You can try to run the suggested cmake-format command over the original CMakeLists.txt and compare the resulting output file.

@simbit18 I quick look at this CMakefile I didn't see any issue, any idea?

[simbit18]

@DheerajSingh1107 seems like there is some issue with the CMakefile:

ERROR __main__.py:618: Check failed: /home/runner/work/nuttx/nuttx/nuttx/drivers/sensors/CMakeLists.txt

cmake-format check failed, run following command to update the style:
  $ cmake-format <src> -o <dst>

You can try to run the suggested cmake-format command over the original CMakeLists.txt and compare the resulting output file.

@simbit18 I quick look at this CMakefile I didn't see any issue, any idea?

Hi @acassis From what I can see, it’s just a styling error in the CMakeLists.txt file.

Hi @DheerajSingh1107 , you need to fix the file locally.

install cmake-format

https://github.com/apache/nuttx/blob/master/.github/workflows/check.yml#L42C11-L44C72