ESP8266 Community Forum

- Fri Jun 05, 2015 6:03 pm #19611 Your rest block has the same pin definition twice I think.

Yes, 0.1uF/100nF cap on the device power pin is almost always used but you aren't dealing with a device, you're dealing with a module which should already have that bypass cap loaded. By the time you add a bypass cap on your board you are going to be too far away from the ESP8266 chip pin to really filter any noise. The whole point of a bypass cap is to filter noise right before the power enters the chip, adding after the module is close to pointless.

- Sat Jun 06, 2015 3:28 am #19627

Your rest block has the same pin definition twice I think.

Yes, 0.1uF/100nF cap on the device power pin is almost always used but you aren't dealing with a device, you're dealing with a module which should already have that bypass cap loaded. By the time you add a bypass cap on your board you are going to be too far away from the ESP8266 chip pin to really filter any noise. The whole point of a bypass cap is to filter noise right before the power enters the chip, adding after the module is close to pointless.

Well, thanks again The second rest pin should have been GPIO16 (which should be directly connected), the program just renamed it.
I guess I misunderstood the capacitor part, what you are saying sounds quite right. I replaced the capacitor by a 100uF (electrolytic, right?!) cap. I am thinking about adding a cap to the reset pin too like discussed here somewhere (what kind of capacitor would you use there?) and adding ADC capabilities too (voltage divider to 1v?).
I hope once this is done it could help some other newcomers too

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- Sat Jun 06, 2015 8:40 am #19647 It's not critical in this case what type(s) of capacitors are used. You just need to pay attention to polarity and also the voltage rating of the cap. A good general rule is to have the cap voltage rating 2X the voltage that is being applied. Since we're using 3.3V almost any cap will work since the lowest common voltage rating is 6.5V. If you are to purchase caps purchase ones with much higher voltage ratings so if you have a different project you can use the same caps instead of having to buy more parts. Usually the cost difference is very small when moving up in voltage as long as package size is not a concern (higher voltage ratings are typically in larger packages).

Yes, it's a good idea to have a voltage divider on the ADC pin since that pin is limited to a 1V input

- Mon Jun 08, 2015 1:50 pm #19846 Ok here is the next (and hopefully final) version. I added a capacitor to the reset line (is that done right?) and a voltage divider on the adc pin which should break down 3.3V signals to a 01-V range.
Last question remaining for me at the moment: what is the best practice with unused pins in a pcb with the esp? Say I don't need to use the adc and GPIO 14. I guess just leaving them floating isn't the best idea. But what is? Connecting them to ground? With a pulldown?

Thanks again for the help (espacially Georgeloak)!
I hope this might someday help other newbies with esp board development

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