drivers: htu21d relative humidity and temperature sensor driver #10110

gschorcht · 2018-10-04T08:40:05Z

Contribution description

This PR adds a driver for the TE Connectivity HTU21D humidity and temperature sensor. The driver could also be used with Sensirion SHT21 and with SI7021.

The sensor only supports single measurements and polling. This driver provides also drivers/saul capabilities.

Please note:
Even though the HTU21D driver also works with SI7021 sensor for which drivers/si70xx already exists, there are the following differences:

drivers/si70xx checks some registers during intialization that do no exist in HTU21D sensor (heater control register and revision registers).
drivers/si70xx uses clock stretching which blocks the bus and the master during the measurement which can take up to 85 ms. drivers/htu21d does not use clock stretching to avoid this blocking.
drivers/si70xx does not implement the CRC check while drivers/htu21d implement and use it.

As an alternative, I could provide a PR that

defines a pseudomodule for HTU21D,
modifies drivers/si70xx so that it would also work also with HTU21D,
includes wrapper files drivers/include/htu21d.h and drivers/htu21d/include/htu21d_params.h which just redefine symbols with prefix htu21d_, and
includes a tests/driver_htu21d as test application.

I have it already realized also in that way and could provide it. The same could be done for SHT21.
But please keep in mind that a pseudo/wrapper module would use drivers/si70xx which blocks the bus and the master while waiting for measurement results.

Testing procedure

USEMODULE=htu21d make flash -C tests/saul BOARD=...

maribu · 2018-11-13T09:33:34Z

@gschorcht: I could review this PR, but I don't have the hardware to test it. Should I still review?
@basilfx: Maybe you could get involved as author of the si70xx.

To me the advantage of not using clock stretching to allow using multiple I2C device on the same bus is obvious. Is there any technical argument to not use this approach in the si70xx? If not, I personally would favor a unified driver for all devices that would work in a non-blocking fashion, unless one of the following would result:

The resulting unified driver would be bigger than two separate drivers
The resulting driver would perform significantly poorer (e.g. regarding performance, features, ROM size) than each of the two separate driver
The resulting driver would be harder to maintain than two separate drivers (e.g. code gets way more complex)
Simultaneous use of si70xx, htu21d, and sht21 devices would not be possible by one unified driver, but it would be by separate drivers.

Note: I did not look yet into either this code or the si70xx drivers. So maybe the above questions are obvious.

gschorcht · 2018-11-17T14:12:47Z

@maribu Thanks for your offer to review the driver. We should wait some more time for an answer from @basilfx. Once he has answered we can decide whether to redesign the si70xx or to continue with the separate driver.

basilfx · 2018-11-26T10:49:07Z

I'm in the middle of a moving, so I won't be able to test this soon.

stale · 2020-04-10T12:25:08Z

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If you want me to ignore this issue, please mark it with the "State: don't stale" label. Thank you for your contributions.

gschorcht · 2020-04-10T13:05:53Z

PR is waiting for review.

aabadie · 2020-04-10T13:31:38Z

Needs rebase

aabadie

I'm not convinced by the proposed API.

I don't see a real benefit from the user point of view in having a couple functions htu21d_measure_tmp/htu21d_fetch_tmp over a single function htu21d_read_temperature. It would make the API more natural, compared to other sensors. Then USE_HTU21D_BLOCKING could also be removed.

In a way, htu21d_read could be split into 2 functions htu21d_read_temperature and htu21d_read_humidity.

Otherwise, the driver implementation looks good. Maybe you could also add a README.md file with the test application.

aabadie · 2020-04-10T15:38:39Z

drivers/htu21d/Makefile

+MODULE = htu21d
+


Suggested change

MODULE = htu21d

aabadie · 2020-04-10T15:39:19Z

drivers/htu21d/htu21d.c

+    } \
+}
+
+/** Forward declaration of functions for internal use */


Suggested change

/** Forward declaration of functions for internal use */

/* Forward declaration of functions for internal use */

aabadie · 2020-04-10T15:44:18Z

drivers/Makefile.dep

@@ -175,6 +175,10 @@ ifneq (,$(filter hts221,$(USEMODULE)))
  FEATURES_REQUIRED += periph_i2c
 endif

+ifneq (,$(filter htu21d,$(USEMODULE)))
+  FEATURES_REQUIRED += periph_i2c


Suggested change

FEATURES_REQUIRED += periph_i2c

FEATURES_REQUIRED += periph_i2c

USEMODULE += xtimer

Because there's a strong dependency on xtimer in the driver implementation.

aabadie · 2020-04-10T15:46:35Z

drivers/htu21d/htu21d.c

+    return HTU21D_OK;
+}
+
+static const uint8_t _times_tmp[] = { 85, 22, 43, 11 };


Could we have some defines for this constants ?

aabadie · 2020-04-10T15:47:15Z

drivers/htu21d/htu21d.c

+    return HTU21D_OK;
+}
+
+/** Functions for internal use only */


Suggested change

/** Functions for internal use only */

/* Functions for internal use only */

maribu · 2020-04-10T18:21:11Z

This PR adds a driver for the TE Connectivity HTU21D humidity and temperature sensor. The driver could also be used with Sensirion SHT21 and with SI7021.

Could this replace the sth2x and the si70xx driver? If so, I really would love to have less code to maintain to provide the same features.

This would also be greatly beneficial in case someone (for whatever reason) connects a bunch of temperature+humidity sensors of the various flavors, as with the single driver only ROM space for one implementation would be needed.

aabadie · 2020-06-23T15:08:55Z

Please rebase. There are also some pending review comments.

stale · 2020-12-25T17:36:38Z

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If you want me to ignore this issue, please mark it with the "State: don't stale" label. Thank you for your contributions.

stale · 2022-03-02T09:18:40Z

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If you want me to ignore this issue, please mark it with the "State: don't stale" label. Thank you for your contributions.

stale · 2022-09-21T05:50:54Z

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If you want me to ignore this issue, please mark it with the "State: don't stale" label. Thank you for your contributions.

gschorcht added 3 commits October 4, 2018 09:52

drivers: add htu21d device driver

28a62e5

sys/auto_init: add htu21d device driver

bce222b

tests: add htu21d driver test

e75eae4

PeterKietzmann added Type: new feature The issue requests / The PR implemements a new feature for RIOT Area: drivers Area: Device drivers Area: SAUL Area: Sensor/Actuator Uber Layer labels Oct 4, 2018

maribu requested a review from basilfx November 13, 2018 09:23

aabadie added this to the Release 2019.01 milestone Dec 3, 2018

aabadie modified the milestones: Release 2019.01, Release 2019.04 Jan 25, 2019

miri64 modified the milestones: Release 2019.04, Release 2019.07 May 7, 2019

MrKevinWeiss modified the milestones: Release 2019.07, Release 2019.10 Jul 16, 2019

kb2ma removed this from the Release 2019.10 milestone Oct 8, 2019

stale bot added the State: stale State: The issue / PR has no activity for >185 days label Apr 10, 2020

gschorcht removed the State: stale State: The issue / PR has no activity for >185 days label Apr 10, 2020

aabadie requested changes Apr 10, 2020

View reviewed changes

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gschorcht added the State: WIP State: The PR is still work-in-progress and its code is not in its final presentable form yet label Jan 4, 2021

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drivers: htu21d relative humidity and temperature sensor driver #10110

drivers: htu21d relative humidity and temperature sensor driver #10110

gschorcht commented Oct 4, 2018 •

edited

maribu commented Nov 13, 2018

gschorcht commented Nov 17, 2018 •

edited

basilfx commented Nov 26, 2018

stale bot commented Apr 10, 2020

gschorcht commented Apr 10, 2020

aabadie commented Apr 10, 2020

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aabadie Apr 10, 2020

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maribu commented Apr 10, 2020

aabadie commented Jun 23, 2020

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stale bot commented Mar 2, 2022

stale bot commented Sep 21, 2022

	/** Forward declaration of functions for internal use */
	/* Forward declaration of functions for internal use */

	FEATURES_REQUIRED += periph_i2c
	FEATURES_REQUIRED += periph_i2c
	USEMODULE += xtimer

	/** Functions for internal use only */
	/* Functions for internal use only */

drivers: htu21d relative humidity and temperature sensor driver #10110

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drivers: htu21d relative humidity and temperature sensor driver #10110

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gschorcht commented Oct 4, 2018 • edited

Contribution description

Testing procedure

maribu commented Nov 13, 2018

gschorcht commented Nov 17, 2018 • edited

basilfx commented Nov 26, 2018

stale bot commented Apr 10, 2020

gschorcht commented Apr 10, 2020

aabadie commented Apr 10, 2020

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gschorcht commented Oct 4, 2018 •

edited

gschorcht commented Nov 17, 2018 •

edited