drivers/dht: initial import #2990

LudwigKnuepfer · 2015-05-15T21:31:47Z

Unified driver for DHT11 and DHT22.
Test application included.

LudwigKnuepfer · 2015-05-15T22:35:52Z

There are some cleanup activities left.. Will tend to this PR again tomorrow.

Anyway:
Both sensors were tested with sub-zero temperatures, the DHT11 was also tested for > 60 degrees C which resulted in a slightly burnt/molten case. All readings made sense.

mehlis · 2015-05-16T07:16:42Z

drivers/dht/dht.c

+            /* read 1, set bit */
+            les_bits |= 0x0000000000000001;
+            /* wait for low */
+            while (gpio_read(dev)) ;


I think this line is a leftover of the previous approach with using sleep.

LudwigKnuepfer · 2015-05-16T11:05:12Z

Can't test anymore, my sensor died.

jnohlgard · 2015-05-16T11:09:12Z

@LudwigOrtmann

Can't test anymore, my sensor died.

Did it die because of this PR? 😜

LudwigKnuepfer · 2015-05-16T11:41:16Z

@gebart Due to the cause chain: definitely ;)
But really, I'm not sure, it went hot and ~~stopped responding~~ didn't respond when I wanted to test the patches.
I did not test yesterdays state again today. Could be a wiring mishap or the result of yesterdays heating accident.

LudwigKnuepfer · 2015-05-16T11:52:34Z

Doesn't even look too bad and did still work yesterday...

miri64 · 2015-05-16T12:54:55Z

RIP

LudwigKnuepfer · 2015-05-16T21:44:13Z

Tested patches with an intact DHT22, worked as expected.

PeterKietzmann · 2015-05-18T12:02:03Z

drivers/dht/dht.c

+
+void dht_parse_22(dht_data_t *data, float *outhum, float *outtemp)
+{
+    *outhum = data->humidity / 10;


I didn't find this in the datasheet immediately but I guess this has to do with the higher resoultion of the dht22?

yes, also it's what the datasheets say the conversion is

PeterKietzmann · 2015-05-18T12:09:43Z

@LudwigOrtmann the driver looks good to me besides some minor comments. I don't have the hardware to test it. I never "researched" on it but I thought about a common 1-wire interface for the future. After implementing this rudimentary protocol, do you think it makes sense so create a common 1-wire API?

jnohlgard · 2015-05-19T04:11:21Z

@PeterKietzmann I don't think the DHT22 is really 1-wire (I'm assuming you were referring to the 1-wire brand name by Maxim Integrated). From the data sheet the DHT22 seems similar but the length of each bit depends on if it is a zero or a one, which it does not in the (Maxim) 1-wire protocol.

LudwigKnuepfer · 2015-05-19T05:43:43Z

I superficially looked into this as well and can confirm that the DHT family is not speaking "1-wire". While it has some similarities, I wouldn't base a unified communication module on it.

PeterKietzmann · 2015-05-19T06:30:59Z

Thanks for your answers. Well, if it is proprietary, I agree there is no reason for an interface...

PeterKietzmann · 2015-05-20T20:42:20Z

Does anyone have the hardware to test this driver?

haukepetersen · 2015-05-20T21:52:54Z

drivers/include/dht.h

+ * @param[out]  hum     pointer to variable humidity is stored to
+ * @param[out]  temp    pointer to variable temperature is stored to
+ */
+void dht_parse(dht_t *dev, dht_data_t *data, float *hum, float *temp);


Same as in #2980: I would prefer to have three functions here:

void dht_read_raw(); // return raw values void dht_read(dev, int32_t *tmp, int16_t? *hum); // return milidegree C and mg/m^3 void dht_read(dev, float *tmp, float *hum); // return degree and g/m^3

void dht_read_raw(); // return raw values

As a side-effect?

Hm, probably not .. anyways - I think the parse function allows for higher flexibility regarding reading and transforming of the values. I can add convenience functions that call both in one go if you insist.

yes, I do. In the end, in 99% of the cases, users are not interested in the raw value, but in the actual physical ones. So forcing them to call parse after any reading reduces IMHO the usability of the driver...

Could you elaborate on how an explicit parse function increases the flexibility?

You can read values at one and convert them at a later point in time. I imagine this might be useful in a time constrained situation.

I'm not going to implement an optimized integer reading version any time soon, knock yourself out in a follow-up PR.

Looking at the timings for the sensor and the time it takes for the conversion I say the conversion time is insignificantly small... But if you will not fix it anyway, fine with me.

LudwigKnuepfer · 2015-05-24T17:26:19Z

@haukepetersen @PeterKietzmann can I squash?

PeterKietzmann · 2015-05-26T07:11:24Z

@LudwigOrtmann the code looks good to me. Can anyone test the driver? Maybe @mehlis has a device? Let's wait with squashing until tested.

OlegHahm · 2015-05-26T07:25:44Z

Why do we need with squashing for a test?

PeterKietzmann · 2015-05-26T07:26:55Z

Honestly I don't really know :-) ! Fine, please squash. ACK when tests went positive

LudwigKnuepfer · 2015-05-28T13:59:19Z

Why do we need with squashing for a test?

I don't understand the question.

haukepetersen · 2015-05-28T14:04:19Z

ACK when suqashed and Travis happy.

Unified driver for DHT11 and DHT22.

PeterKietzmann · 2015-05-29T07:58:23Z

And go

drivers/dht: initial import

LudwigKnuepfer added Type: new feature The issue requests / The PR implemements a new feature for RIOT Area: drivers Area: Device drivers labels May 15, 2015

LudwigKnuepfer assigned PeterKietzmann May 15, 2015

LudwigKnuepfer force-pushed the pr/dht branch 2 times, most recently from 5608489 to c109b18 Compare May 16, 2015 07:08

mehlis reviewed May 16, 2015
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LudwigKnuepfer force-pushed the pr/dht branch from 123613e to f75de65 Compare May 16, 2015 10:19

OlegHahm added the CI: needs squashing Commits in this PR need to be squashed; If set, CI systems will mark this PR as unmergable label May 16, 2015

PeterKietzmann reviewed May 18, 2015
View reviewed changes

LudwigKnuepfer force-pushed the pr/dht branch from 14c556c to 8c5d8b9 Compare May 20, 2015 19:34

haukepetersen reviewed May 20, 2015
View reviewed changes

LudwigKnuepfer force-pushed the pr/dht branch from 8c5d8b9 to ae926f5 Compare May 23, 2015 09:13

OlegHahm modified the milestone: Release 2015.06 May 28, 2015

LudwigKnuepfer added 2 commits May 29, 2015 06:24

drivers/dht: initial import

4a05f47

Unified driver for DHT11 and DHT22.

test/driver_dht: initial import

fe17cae

LudwigKnuepfer force-pushed the pr/dht branch from ae926f5 to fe17cae Compare May 29, 2015 04:24

LudwigKnuepfer removed the CI: needs squashing Commits in this PR need to be squashed; If set, CI systems will mark this PR as unmergable label May 29, 2015

PeterKietzmann added the CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR label May 29, 2015

PeterKietzmann added a commit that referenced this pull request May 29, 2015

Merge pull request #2990 from LudwigOrtmann/pr/dht

b771e91

drivers/dht: initial import

PeterKietzmann merged commit b771e91 into RIOT-OS:master May 29, 2015

LudwigKnuepfer deleted the pr/dht branch May 29, 2015 16:54

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drivers/dht: initial import #2990

drivers/dht: initial import #2990

LudwigKnuepfer commented May 15, 2015

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mehlis May 16, 2015

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drivers/dht: initial import #2990

drivers/dht: initial import #2990

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LudwigKnuepfer commented May 24, 2015

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