ESP8266 Community Forum

- Sun Aug 21, 2016 9:14 am #53488 Hi Guys! First post here. Before I talk about the specific problem, I thought I will give a small introduction.

I am a newbie and I recently started exploring ESP-01 for fun sake. First, I wanted to reflash the ESP-01 with a new firmware using FTDI USB to TTL converter (FTDI 232R). I understand now that this is not the ideal way to start learning about ESP-01 Anyways, I read a lot of blogs/forums without any success and I was getting nowhere. Recently, I read this blog (https://vilimpoc.org/blog/2016/05/04/es ... -shootout/), knew what the problem was (replaced the FTDI with CH340G) and bam, I had success!! Thanks to the blog owner

I am now looking at interfacing the ESP-01 with a UNO. Again, I read a post (http://iot-playground.com/blog/2-uncate ... connection) and I am not particularly convinced that the hardware circuit will work robustly. My understanding is that a resistor divider to connect Arduino Tx to ESP-01's Rx will not provide enough current/voltage level for reliable operation (cue: 20mA DC current per Arduino I/O pin and 56 mA typical consumption of ESP-01's Rx operation). My second concern is the other part of the connection i.e. Arduino Rx <---> ESP-01 Tx. In the same previously mentioned link, a direct connection is advocated as well as a transistor based level shifter. I do not believe a direct connection is a good idea as it may fry the UNO (cue: 170mA typical Tx operation current of the ESP-01). I have no idea if the transistor does it safely.

Does anyone have a better (read: safe and reliable) hardware circuit to achieve this? I have pondered over using a bi-direction logic level converter but am not sure if the current constraints are met. Any help is greatly appreciated

- Mon Aug 22, 2016 10:46 am #53586

56 mA typical consumption of ESP-01's Rx operation

(cue: 170mA typical Tx operation current of the ESP-01

I don't know where you are getting this from but you seem to be misreading it. The RX and TX pins do not consume that current. I expect that what you have there is current consumption of the CPU from the 3.3V power supply. (in the case of the ESP8266)

I don't have time to go into an explanation. (at work now) But based on my quick look at the page you referenced what was done there looks reasonable.

- Tue Aug 23, 2016 4:46 am #53645 Hi! Thanks for the reply. I might be misreading information. I got the stats from here:

http://bbs.espressif.com/viewtopic.php?t=133
wiki/doku.php?id=esp8266_power_usage

Am I right in understanding that the current might be insufficient?

- Tue Aug 23, 2016 7:18 am #53652 That is the current from the power supply. Not into or out of the TX or RX pins. The same applies for the UNO. Using the RX and TX lines does not mean the current for operation comes from those lines. Like I said, you are misapplying what you are reading.

Think of a Car. You only need a little pressure on the gas pedal to move a lot of weight. And that consumes energy. But that energy is not coming from the gas pedal. Same thing with the RX and TX lines. They are just control signals. They don't power the system.