ESP8266 Community Forum

- Wed Apr 06, 2016 10:47 am #44965 What charge controller are you trying to gather data from? Are you sure the DB9 has true RS232? Perhaps RS432 or RS485?

If its truly a RS232 output you need to convert that to TTL, There are a bunch of modules on ebay to do this or you can use the Maxum MAX 232 chip to do it yourself. Once you get it to TTL you need to drop it further for the 3v needed by the ESP chip. Many 232 converts have a 3v option if not then a simple voltage divider on the TX from the device will work. Dont worry about tyhe 3v form the ESP.

After that you have at least the signal and can then start decoding the data stream.

Gary

- Wed Apr 06, 2016 6:40 pm #45011

You need to use some interface chip such as MAX232, which built the +-7V out from 5V using internal charge pumps.

ESP8266 are 3v3 devices, so the Maxim chip required here is MAX3232. Do a search for MAX3232 on a site such as dx dot com and there will be lots of interface modules to choose from. Such a module will connect directly to the Txd and Rxd pins on the ESP module.
You don't mention whether your ESP-12E is mounted on a baseboard. If there is a USB to serial converter chip on the baseboard then the situation is different.

- Wed Apr 06, 2016 10:29 pm #45017 Is there some ready-made board say with a DB9 or direct pin connections?

BTW, it is even worst : real RS232 signal is swinging between around -7V and +7V, inverted compared to TTL side, -7V is HIGH and +7V is LOW.

You need to use some interface chip such as MAX232, which built the +-7V out from 5V using internal charge pumps.

- Thu Apr 07, 2016 2:23 am #45024 Yes I am actually using a NODEMCU 1.0 as pictured here

http://www.aliexpress.com/item/New-Wire ... .28.T0bIJM

Would something as the following be required

http://www.ebay.com/itm/270772788718?eu ... 843d7&cp=1

You need to use some interface chip such as MAX232, which built the +-7V out from 5V using internal charge pumps.

ESP8266 are 3v3 devices, so the Maxim chip required here is MAX3232. Do a search for MAX3232 on a site such as dx dot com and there will be lots of interface modules to choose from. Such a module will connect directly to the Txd and Rxd pins on the ESP module.
You don't mention whether your ESP-12E is mounted on a baseboard. If there is a USB to serial converter chip on the baseboard then the situation is different.