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Compilation error with PCF8575  [SOLVED]

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Post Number:#1 Post Wed Jun 27, 2018 3:27 pm
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I have a problem with the PCF8575 module, if I compile indicating that I am using it, the screen remains blank while if I indicate that I am not using it correctly. I enclose the scheme of the circuit that I am using and that I believe is correct. Could it be that the module is defective ?.

It is as if it were not connected and I have verified that pins 20 and 21 have continuity and that the 5 Vs arrive correctly.

Am I doing something the wrong way?

As soon as a new PCF8575 arrives I will change it, but on the other hand I find it strange that it fails

Image

Regards

Post Number:#2 Post Wed Jun 27, 2018 5:14 pm
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Hi!

White screen is because the controller can't find your PCF.

Try the "I2C scan" test code to see if the controller can find the PCF.

The address should be 0x20.

Best regards.
Please do not PM me for support unless it is absolutely necessary.

I'll not write custom function to nobody unless you can pay for my job.

Post Number:#3 Post Wed Jun 27, 2018 5:28 pm
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Hi, can not find it. I suppose that if the circuit that I have attached is correct, the fault is in the PCF8575 itself.

Would you be so kind as to confirm that the circuit of the scheme is correct?

If so, I will proceed to change my PCF module

Thank you

Post Number:#4 Post Wed Jun 27, 2018 5:32 pm
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Where your 5 V and GND are connected?
Please do not PM me for support unless it is absolutely necessary.

I'll not write custom function to nobody unless you can pay for my job.

Post Number:#5 Post Thu Jun 28, 2018 3:17 am
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The 5v are powered by an external power source and GND is common. I have verified that between the pin VCC and GND of the PCF8575 arrive 5V.

Post Number:#6 Post Thu Jun 28, 2018 8:36 am
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In this picture GND and 5 V are floating.

Do you have a RTC module? Try connect to this header to check if SDA and SCL are ok.
Please do not PM me for support unless it is absolutely necessary.

I'll not write custom function to nobody unless you can pay for my job.

Post Number:#7 Post Thu Jun 28, 2018 9:46 am
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If I have left them floating to simplify the scheme but they are really connected. I have also hidden the RTC module but it is actually connected to pins 18 and 19 and powered on the same line as the PCF and works correctly.

Finally I designed a complete plate instead of the different modules to simplify the wiring. I think there may be a problem in the PCF itself and this very afternoon I will replace it to make sure.

I was asking if I found any errors in the scheme and it saves me from desoldering and re-soldering a new PCF module

regards

Post Number:#8 Post Thu Jun 28, 2018 5:24 pm
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Finally it was the PCF8575 that did not work, I just replaced it and it worked perfectly.

I only have to connect the Atlas modules to finish the project and well, design the boxes to contain it.

Attached a couple of photos of the base plate and the plate of the dosing pumps.

Image

Image

Thanks !!

Post Number:#9 Post Fri Jun 29, 2018 8:37 am
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Glad to hear!

You are doing a great job.
Please do not PM me for support unless it is absolutely necessary.

I'll not write custom function to nobody unless you can pay for my job.




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