I bought an ESP-01 adapter (initially I thought this was the WIFI module):

ESP-01 adapter

Than I bought the 'real' ESP-01 (which is not arrived yet):


However, according to this link: connect (sorry it's in Dutch), but the picture shows that the ESP-01 is directly connected to the 3.3V of the Arduino.

My question: why bother using the adapter card? Or does it give additional security/protection (and what)?


Using an ESP8266 with a traditional Arduino requires logic level translation of the UART signal. That is what this adaptor provides. It also provides a dedicated 5V -> 3.3V voltage regulator so you don't stress the Arduino's rather underpowered 3.3V regulator.

The two SOT-23 components are N-channel MOSFETs (probably BSS138P or similar), and the SOT-89 component is the voltage regulator.

Yes, you can provide all that yourself, to varying levels of complexity - this just makes things easier. And since you already have it you may as well make use of it.

  • Thank you very much ... I assume with logic level translation you mean also a 5V-3.3V translation (but for the data?) ... I will start using both than ... but eventually I will need more (thanks to your good idea to use multiple Arduinos). – Michel Keijzers May 31 '17 at 9:28
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    Yes, the logic level translation converts the 5V TX from the Arduino into the 3.3V RX of the ESP8266, and the 3.3V TX of the ESP8266 into a 5V RX to the Arduino (the latter is not strictly needed, but helps to improve noise immunity). – Majenko May 31 '17 at 9:29
  • Ah thanks .. and that probably explains also why sometimes I read RX needs to be connected to TX and vice versa instead of RX<->RX and TX<->TX – Michel Keijzers May 31 '17 at 9:31
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    You connect RX->RX and TX->TX if you are using the Arduino as a UART interface (disabling the ATMeag328P by holding reset LOW or physically removing the chip). Otherwise you connect RX to TX and TX to RX (the Arduino pins in this latter case are usually chosen by you and used with SoftwareSerial since the UART pins are used by your USB connection). – Majenko May 31 '17 at 9:33
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    you won't get 1ms times with wifi. i think my best half-legs are about 15ms. this is due to http overhead – dandavis Jun 1 '17 at 3:38

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