MCP23017 question

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Sasch600xt
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MCP23017 question

#1 Post by Sasch600xt » 02 Mar 2019, 19:50

Hello all :)

may i have a probably dumb question but i cant find the answere.

i need to send out 4 analog values from ESP (0-3.3V / 0-255)

I have a MCP23017 connected to ESP.
Can i do it with a MCP ?
And if yes, how would the syntax look like ?
If NO, is there a way to get 4 analog output pins working with ESP (like a "analog output port expander") ?

See ? Dumb question :)

Thanks for help :)
Sascha

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budman1758
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Re: MCP23017 question

#2 Post by budman1758 » 02 Mar 2019, 19:59

Methinks the best way is to use an ADS1115 A-D Converter chip. MCP23017 is only for on,off or pulse stuff.

No such thing as a dumb question. Nobody falls out of their mama knowing everything. :mrgreen:
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HomeJCL
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Re: MCP23017 question

#3 Post by HomeJCL » 02 Mar 2019, 20:30

ADS is an AD.

In this case the question is for an DA output stage.

I am also interested if anybody has the answer.
Belgium and land of ESP ... counting :D

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budman1758
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Re: MCP23017 question

#4 Post by budman1758 » 02 Mar 2019, 20:58

What is the source of these values? How does the ESP get the values in the first place?
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Sasch600xt
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Re: MCP23017 question

#5 Post by Sasch600xt » 02 Mar 2019, 21:37

i want to send MQTT Messages to the ESP.

like:

http://192.168.123.45/control?cmd=ANALOG_OUT,1,255
http://192.168.123.45/control?cmd=ANALOG_OUT,2,127
http://192.168.123.45/control?cmd=ANALOG_OUT,3,0
http://192.168.123.45/control?cmd=ANALOG_OUT,4,200

this sends the value to a 4ch dimmer (0-3.3volt expected)

So lets google for a ADS1115 A-D Converter chip :)
Is there a plugin already for ESP Easy ?

Thank you all for your Help :)
Sascha

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budman1758
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Re: MCP23017 question

#6 Post by budman1758 » 02 Mar 2019, 21:51

Not sure you need the ADS1115 here as I am still a bit confused as to what the ESP is actually doing here. You say you want to send these analog values TO the ESP. I assume they then go out to a dimmer of some sort?

Maybe a picture or a diagram or schematic would be helpful.
Last edited by budman1758 on 02 Mar 2019, 22:18, edited 1 time in total.
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Sasch600xt
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Re: MCP23017 question

#7 Post by Sasch600xt » 02 Mar 2019, 22:06

http command ---> ESP Easy -----> 4 times analog 0-3.3Volt out ------> 4 CH Dimmer

I see the ADS1115 is for analog INPUT, but i need to have analog OUTPUT.

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budman1758
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Re: MCP23017 question

#8 Post by budman1758 » 02 Mar 2019, 22:28

I think what you need to do is convert PWM output to a voltage.
See this for inspiration.
https://www.instructables.com/id/Analog ... o-Voltage/
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Sasch600xt
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Re: MCP23017 question

#9 Post by Sasch600xt » 02 Mar 2019, 22:50

Perfect !!!

Sasch600xt
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Re: MCP23017 question

#10 Post by Sasch600xt » 02 Mar 2019, 23:05

Now another question :)

i dont understand in doku:
MCPPulse,<pin>,<value>,<duration> 1,0 Pulse control on MCP23017 output pins (duration in mS, MILLIseconds)

so how would a http command look like for MCP port 1 with a pwm of 127 ( i assume value can be from 0-255) ?

Thank you so much
Sascha

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budman1758
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Re: MCP23017 question

#11 Post by budman1758 » 03 Mar 2019, 00:57

I'm not sure the MCP23017 supports PWM. That's a question for the devs. Some of the native ESP GPIO support PWM. Might be easier to use those.

Or a dedicated PWM output chip module.
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Sasch600xt
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Re: MCP23017 question

#12 Post by Sasch600xt » 03 Mar 2019, 09:12

i have a PCA9685 here and i will try one of those :)

Sasch600xt
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Re: MCP23017 question

#13 Post by Sasch600xt » 03 Mar 2019, 10:47

i do not get a signal out of the PCA9685 ?

It shows up after "scan for i2C device".

So i try:
http://192.168.123.45/control?cmd=PCAPWM,1,4095

and get:
{
"log": ": PWM 1",
"plugin": 22,
"pin": 1,
"mode": "PWM",
"state": -1
}

any ideas ?
Thank you for your help

kimot
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Re: MCP23017 question

#14 Post by kimot » 03 Mar 2019, 22:00

You can use this motor PWM like DA converter for convert digi to analog via i2c:
https://www.letscontrolit.com/wiki/inde ... 2#Hardware

So by TB 6612

Sasch600xt
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Re: MCP23017 question

#15 Post by Sasch600xt » 04 Mar 2019, 19:50

yes, but i have already a PCA9685 and there is a plugin for in ESP Easy.
plus budman showed a very good and very small solution to get a analog signal out of a pwm signal.

the only question right now is why does the PCA9685 not work ?
i must do something wrong here.

Thanks for help
Sascha

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