Skip to main content

A simple ESP-01 USB adapter with toggle switch for reprogramming

ESP-01 is a simple ESP8266 module which can be purchased cheaply from Aliexpress. At one of promotion, I purchased an ESP-01 for just S$1.97. That's very cheap for a wifi enabled microcontroller. An ESP-01 can be a WIFI bridge for non-connected microcontroller such as Arduino UNO, Mega, Nano etc. Communication between the microcontroller can be done using the serial link between them.

I have written a post on this using ESP-Link to connect to an Arduino Pro Mini. Together with the client library provided, the Pro Mini can easily transfer sensor data via MQTT.

For the most part, once the firmware is in place, normally I will use OTA to update. Sometimes, I wanted to reuse the same controller for another firmware and I have rewired up the controller for reflashing. This makes it very inconvenient to use.

Recently, I bought a USB ESP-01 adapter thinking that my problem is solved. When I received it and realised that it is cannot be a programmer so I decided to wire up a toggle switch.

The GPIO0 is wired to the centre pin and one of the pins is pulled up to VCC (Normal Operation) and the other pin is wired to ground (Programming Mode).
After some soldering and covering the exposed parts using a glue gun, the final output looks like this. Not very nice but workable. 
Instead of soldering and glueing, you can also purchase an adapter with the toggle switch. The price difference is about S$2-$3 compared to those without.


Popular posts from this blog

Using ESP-Link transparent bridge (ESP-01 and Arduino Pro Mini)

Recently stumbled across an interesting open source project ESP-Link. Its main purpose is to network-enable a non-network microcontroller (MCU) such as Arduino Uno, Pro mini or Nano using ESP8266. The author termed it as "Transparent Bridge". The ESP and MCU  communicate via the serial link and there is a companion Arduino library EL-Client for the MCU to connect up the network using MQTT, REST, TCP and UDP.
Setup I have put together an ESP-01 and an Arduino Pro Mini for this experiment. I have chosen a 3.3 version Pro mini so that I do not need to do any voltage level shifting between the I/O pins. In order to have a stable voltage source, the ESP8266 is powered by Pro Mini and the Pro Mini "RAW" pin is connected to a 5v USB power source. The RAW pin can take voltage up to 12V. The reset pin of Pro Mini is connected to GPIO 0 of ESP-01. This enables the ESP-01 to reset the Pro Mini.

I have linked up an APDS 9960 sensor to it and periodically send the luminosity a…

Using ESP-Link transparent bridge (ATmega2560+ESP8266 board)

I have found this interesting board selling on Aliexpress website. It is an Arduino Mega 2650 with a built-in ESP8266 which allows the Mega to connect to wifi. This board has cut down a lot of wiring and bring out interesting possibilities. One of this is to connect up both the microcontrollers using ESP-link firmware. I have an earlier blog post that described how to wire up an ESP-01 and Arduino Pro Mini.

One of the tricky parts in this setup is the sequence of flashing the ESP firmware. Flashing the onboard ESP8266 requires some setting changes to the dip switches. The following are the sequences which I get both the microcontrollers to talk to each other.
Set the jumper 5,6,7 to ON and the rest OFF. This will set the ESP to update mode.I am using version 3.0.14 and flashed the ESP using the following parameters:
esptool --port com26 --baud 230400 write_flash -fm dio -fs 4MB -ff 80m 0x0 boot_v1.6.bin 0x1000 user1.bin 0x3fc000 esp_init_data_default.bin 0x3fe000 blank.bin After flash…

DIY Sonoff RF Bridge

Tasmota recently supported the RF bridge by iTead which allowed for RF 433 remote devices to be controlled/controlling using Sonoff products. e.g A handphone can be used to control a remote RF device or an RF remote control can use to control a WIFI enabled device.

By using Tasmota, I can control the device using MQTT. This idea fits exactly to my smart home plan. Here is the schematic:

I cheated a bit by having ESP01 mounted on a breakout board. This breakout board converts all the external pins to 5v which simplified the wiring and I do not need to use a voltage level shifter. Moreover, the Arduino 3.3v power does not have enough current to power the ESP reliably and I have to power it via the 5V from Arduino Uno. Next, I used an Arduino Uno prototype shield with a tiny breadboard to hold all the components together. For the RF 433 transmitter/receiver, I am using the development kits when I purchased the all-in-one Arduino development kits. An antenna is added for more sensitivity.