Many times, you may not have a USB to Serial converter to upload code into chips or communicate with the chip. In this Arduino electronics tutorial we will show how you can use Arduino as a serial USB programmer or as a USB to TTL converter to upload code into ESP8266 WiFi module. Thus you use Arduino instead of the populat FT232RL USB to UART TTL Module. This is because Arduino has USB to TTL converter built into the board and we can make use of it to program devices like the ESP12E WiFi module or any device or MCU like PIC micrcontroller which requires serial USB converter.
The following video demonstrates how to upload code to esp8266 using arduino uno as a USB to TTL converter.
The following picture shows how ESP12E wifi module is interfaced with Arduino Uno(other Arduino also works) for upload code into ESP12E module.
The circuit schematic of Arduino Uno as USB to TTL converter for programming ESP8266 WiFi module is shown below.
In the above circuit wiring drawing, the Arduino reset pin is connected to its ground. This is done so that the USB connection directly connects to the USB to TTL converter chip on the Arduino board. By doing this, means that the Rx and Tx pin of Arduino interchange. That is now, the Tx pin becomes RX and vice versa. The Arduino Tx pin is connected to the ESP8266 TX pin and Arduino Rx pin is connected to the ESP8266 Rx pin. That is all that is required to make Arduino to work as a serial USB converter.
Thus, Arduino is an alternative for FT232RL USB to UART TTL so you don't have to buy USB to TTL converter separately. If you have already Arduino then you can Arduino as USB to serial converter thus you will have a DIY USB to TTL converter.
