working code for sigma delta generator #4119

stefaandesmet2003 · 2018-01-08T23:10:10Z

provide a simple interface to attach/detach pins to the sigma-delta generator, and get/set the 2 parameters prescaler & target

devyte · 2018-01-09T00:04:47Z

@stefaandesmet2003 this is for #4119 , yes? I see you figured it out :)

stefaandesmet2003 · 2018-01-09T07:31:21Z

Yes, indeed

devyte · 2018-01-10T20:11:56Z

cores/esp8266/sigma_delta.h

+The sigma delta source remains on until :
+6. sigma_delta_disable()
+
+copy this code as example :


This example should be made into a working example that builds with the rest of the core, so that at least build issues can be tracked.

Good idea. The example would then be under libraries\esp8266\examples ?

earlephilhower · 2018-01-15T21:19:40Z

libraries/esp8266/examples/SigmaDeltaDemo/SigmaDeltaDemo.ino

+  THE sigma delta output frequency is defined by the ESP8266 hardware as:
+
+  FREQ = 80,000,000/prescaler * target /256  HZ,          0<target<128
+  FREQ = 80,000,000/prescaler * (256-target) /256  HZ,    128<target<256


Are these constant even in 2x mode where CPU_F = 160,000,000?

Good point, i never tested 160MHz. Will verify and correct accordingly!

Checked : CPU frequency has no influence on the SD frequencies

earlephilhower · 2018-01-15T21:21:08Z

libraries/esp8266/examples/SigmaDeltaDemo/SigmaDeltaDemo.ino

+  For higher value capacitors, it might be necessary to add a high-speed buffer between the esp8266 output and RC-filter to limit the current ac load on the 
+  pin output driver.
+
+*/


Could you please add attribution and license (CC0 or PD) to the example header?

PD i guess?

earlephilhower

Overall good stuff here! Some minor suggestions and inquiries to make sure it's easy for Arduino users who might not be up on the internals.

earlephilhower · 2018-01-15T21:33:29Z

sigma_delta.h

+void sigma_delta_setTarget(uint8_t target);
+uint8_t sigma_delta_getPrescaler(void);
+void sigma_delta_setPrescaler(uint8_t prescaler);
+


This is good, but I think to be most useful to end users, who may not be as familiar w/ clock dividers and sigma-delta operation a simpler API might be helpful.

I'd recommend renaming "setTarget/GetTarget" to simply, "write" or "read" as effectively they're trying to write an analog value and "target," while the name used by the hardware designers in the HDK, doesn't really mean much if you don't understand the error-diffusion behind things.

I'd also suggest a simpler "setFrequency(long f) setter method that would do the math described in the header and figure out the closest prescaler given the F_CPU. That'd make end-user code simpler to understand.

Not sure if I fully understand the setFrequency idea. Every call to 'write' (setTarget) would need to adapt the prescaler as well to fit this chosen frequency? And remove the setPrescaler/getPrescaler functions altogether?
There was some sample code like this in an earlier post to this issue. In many cases the effective output frequency is way off the chosen frequency f. Suppose you chose 1 MHz. With 50% duty cycle the closest you get is 312.5kHz. So you give the user the impression that the generator can be used as a fixed frequency source, but in fact it cannot.

Good point, I withdraw this silly request. :) I was thinking this would be useful for someone to, say, drive a 4-pin PWM fan where they'd need to set frequency = 25khz, duty = %age, but it seems it's not really precise enough for such a use, anyway.

For the examples, please do add the Public Domain attribution. I think the team is trying to get these examples cleaned up and that's an easy thing to do.

Apparently ESP32 has an implementation similar to what you suggested. I modified the code to be compatible. ESP32 has apparently 8 independent channels, esp8266 has only 1. Apart from that, the behavior is the same (eg. in terms of output frequencies.) So it makes sense to align the programming interfaces.
Arduino-esp32 also provides a working sigma delta example; there it's not necessary to explicitly include the sigma_delta.h file in the example code; it would be convenient if this was the same in arduino-esp8266, but my example currently doesn't work without the explicit include

earlephilhower · 2018-01-15T21:33:57Z

libraries/esp8266/examples/SigmaDeltaDemo/SigmaDeltaDemo.ino

+  For higher value capacitors, it might be necessary to add a high-speed buffer between the esp8266 output and RC-filter to limit the current ac load on the 
+  pin output driver.
+
+*/


Could you please add attribution and license (CC0 or PD) to the example header?

earlephilhower

Now that 2.4.1 is out this can be queued for the 2.5.0 merge. Only a couple minor things. Thanks!

earlephilhower · 2018-03-09T04:03:10Z

cores/esp8266/core_esp8266_sigma_delta.c

- * Parameters   : none
- * Returns      : uint8 prescaler, CLK_DIV , 0-255
+ * FunctionName : sigmaDeltaRead
+ * Description  : set the duty cycle for the sigma-delta source


Typo here...this "get the duty..."

earlephilhower · 2018-03-09T04:05:24Z

cores/esp8266/core_esp8266_sigma_delta.c

@@ -0,0 +1,152 @@
+#include "Arduino.h" // using pinMode


Needs standard licence header, please.

earlephilhower · 2018-03-09T04:06:04Z

cores/esp8266/core_esp8266_sigma_delta.c

+}
+
+/******************************************************************************
+ * FunctionName : sigma_delta_attachPin


Some FunctionName comments got updated to camelCase, but some like this did not.

earlephilhower · 2018-03-09T04:10:44Z

sigma_delta.h

+#ifndef SIGMA_DELTA_H
+#define SIGMA_DELTA_H
+
+#ifdef __cplusplus


The function prototypes here are "extern "C""'d, but the actual function definitions aren't. Any reason not to drop the "extern C" here?

linking stage doesn't work without this. Maybe you know why?
/SigmaDeltaDemo.ino:16: undefined reference to `sigmaDeltaGetPrescaler()'
and the same for all other sigmaDelta functions

Ignore my previous comment. The other "core_esp8266_*" files are all .c. So ignore the request to remove extern C, leave it there. Sorry for the confusion!

Hi @earlephilhower ,
I don't manage to get the style_check right on the travis build. Could you have a look what the issue is, please?
The other builds are ok now.

Will do tonight. I think it's just a matter of getting the examples in Arduino IDE format (i.e. 2 space indent, brackets in the right spot, etc.).

Looks like your problem is DOS linefeeds. Can you save it with Unix ones, that seems to be what IGRR's checker requires to work properly. I can't do it for you as I don't have write permission to your source repo (nor should I, of course!).

cleanup

travis complains about BUILTIN_LED being deprecated

earlephilhower · 2018-03-10T02:39:50Z

I can't upload to your repo, but I can give you the file to upload yourself. Rename to .ino and replace your existing sample and I think you'll be all set:

SigmaDeltaDemo.ino.txt

stefaandesmet2003 · 2018-03-10T09:39:14Z

thanks for your help.
after 2 more attempts it still fails.
I quit,sorry.

earlephilhower · 2018-03-10T16:54:12Z

@stefaandesmet2003 Sorry for the run around! The Windows/Unix line ending difference is just breaking things for you.

I'll try and pull your branch into my Arduino fork, fix it, and open a linked bug just to get this done.

earlephilhower · 2018-03-10T20:07:40Z

Just committed your changes, closing this PR.

working code for sigma delta generator

d746752

provide a simple interface to attach/detach pins to the sigma-delta generator, and get/set the 2 parameters prescaler & target

devyte assigned earlephilhower Jan 10, 2018

devyte added this to the 2.6.0 milestone Jan 10, 2018

devyte requested changes Jan 10, 2018

View reviewed changes

stefaandesmet2003 added 3 commits January 10, 2018 23:00

Merge branch 'master' into master

a11cb99

removed example code from header file

85b9323

example for the esp8266 sigma delta generator hardware

648483c

earlephilhower added the type: enhancement label Jan 15, 2018

earlephilhower reviewed Jan 15, 2018

View reviewed changes

earlephilhower requested changes Jan 15, 2018

View reviewed changes

stefaandesmet2003 added 3 commits January 23, 2018 21:49

Merge branch 'master' into master

46cf8c4

modified interface in line with ESP32 implementation

c5351a0

modified interface in line with ESP32 implementation

a1f8886

earlephilhower modified the milestones: 2.6.0, 2.5.0 Mar 9, 2018

earlephilhower requested changes Mar 9, 2018

View reviewed changes

stefaandesmet2003 added 8 commits March 9, 2018 19:35

changes requested by earlphilhower

385b7a2

cleanup

update for travis style_check

a60f949

Merge branch 'master' into master

6d177fd

remove unused parameter in sigmaDeltaGetPrescaler()

717bdc3

travis doesn't like compiler warnings

4c7ad74

correct comment for travis

0a1189e

changed BUILTIN_LED to LED_BUILTIN

83aeecd

travis complains about BUILTIN_LED being deprecated

remove unused test code

4ebb183

stefaandesmet2003 added 2 commits March 10, 2018 10:13

for travis style_check

ab7204c

another attempt for travis style_check

d67fa53

earlephilhower mentioned this pull request Mar 10, 2018

Testing - Sigmadelta #4494

Merged

earlephilhower closed this Mar 10, 2018

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working code for sigma delta generator #4119

working code for sigma delta generator #4119

stefaandesmet2003 commented Jan 8, 2018

devyte commented Jan 9, 2018

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devyte Jan 10, 2018

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working code for sigma delta generator #4119

working code for sigma delta generator #4119

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stefaandesmet2003 commented Jan 8, 2018

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earlephilhower commented Mar 10, 2018

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