Description
Whether it's for loading a program onto memory, sending commands, receiving output data, or debugging program execution, at some point in every project where we use a microntroller we are required to communicate with the chip using a computer.
As we know, the preferred way in which a computer communicates with (wired) external devices is over the Universal Serial Bus (USB). When it comes to microcontrollers, we find that some of them have the built-in hardware to make use of the interface natively, as is the case for the ATMega32u4 (Arduino Leonardo), whereas others like the ATMega328p (Arduino Uno) don't. We shouldn't be fooled though, the lack of a native USB interface doesn't render a microcontroller useless, some of the chips in this category are widely used due to a variety of reasons: small size, low cost, low power consumption, etc. In addition, they typically have a serial communication interface available over Universal [Synchronous] Asynchronous Receiver Transmitter (UART/USART) hardware.
In order to 'translate' data transmitted over USB into something suitable for the Serial UART/USART interface (and viceversa) we use Integrated Circuits such as the FT232R manufactured by FTDI, or Silicon Labs' CP2102. The tiny breakout board in this product listing provides a convenient way for using the FT232R for this purpose. On one end it holds a USB micro-B connector, and on the other, a 6-pin female socket with the following pinout:
- GND: Ground Supply
- CTS: Clear To Send Control Input (handshake signal)
- PWR: 3.3V or 5V Output (configurable pin jumper)
- TXO: Transmitted Data (outbound)
- RXI: Received Data (inbound)
- DTR: Data Terminal Ready Control Output (handshake signal)
Usage
By following the connection guide below we can start sending/receiving serial data to/from our Serial UART-capable microcontrollers right away:
The target devices typically used with this board include:
- Arduino Pro / Mini / Uno (although the Uno has its own USB to Serial UART chip)
- Boarduino
- Sound Synthesizer Kit
Inline Reset Capacitor
While using other FTDI Breakout Boards we may have come across the dreaded "not in sync" error when uploading a program onto an Arduino:
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51
avrdude done. Thank you.
The solution has been to add an external, in-series capacitor between the DTR pin on the FTDI Breakout and the RESET pin on the Arduino. The version in this listing makes our lives easier by already including the capacitor onboard, so that the DTR line can be connected directly to the Arduino or any other suitable target device.
Cable
Any USB-A Male to micro-B USB Male cable such as the ones we use to power up our Raspberry Pi should work with this device.
Power
This FT232R Breakout Board allows us to choose whether or not to supply power to the target device. If the target device is already powered, we can simply remove the included 2-pin jumper from the 4-pin male header on the board. However, if we do want to supply power to the target device we can select between an output voltage of 3.3V or 5V. Caution should be exercised when working with microcontrollers that operate at 3.3V!
Driver
Depending on our Operating System we might need to download and install a driver that allows the computer to recognize the FTDI chip. Linux distributions such as Ubuntu already have the driver installed out of the box, but for Mac OS and Windows the appropriate drivers can be found on the official page at FTDI's website.