Archive for the ‘ Microcontroller ’ Category

cheapest usb-to-serial cable.

T6X USB to TTL serial cable

T6X USB to TTL serial cable

If you play with microcontrollers and embedded systems like SOHO routers, you may need a serial connection to monitor your target and sometime (everytime) realize that it don’t really work as expected.

The lucky of you may have old enough computer to  have a real RS232 serial port with the db9 socket and can use this interface with a TTL target thought the traditional max232.

But for the others, the recent computer have no longer this interface, so the only inteface available is the USB.

With a quick search on the Internet you can find USB to TTL-serial on several microcontroller-related website such as sparkfun, seeedstudio, nkc electronics, Adafruit Industries from approx $14 to $20 or on Ebay as low as $8.50 here.

But my best finding is the USB cable (see image) sold with my chinese RC transmitter (a Turborix 6ch 2.4GHz). It’s given as a « programming cable » without any other information. The truth is that this cable is nothing else than a USB to TTL-serial cable. Its price is as low as $2.99

The dongle is based on the Silabs’ cp2102 chip and provide only TX, RX and GND with the 3 wire cable but I plan to change it  to use a 4 wire cable with the fourth wire soldered on the USB’s VCC (5V). By this simple mod I would be able to USB power some little MCU’s projects.

The drivers  are available on the manufacturer site , for the most of the OS , including Linux, MacOS, Windows CE/2000/XP/Server 2003/Vista/7 (note that it was recognize « out-of-the-box » as ttyUSB0 and works on ubuntu and probably on others linux)

For the mini-DIN plug at the end ot the cable, don’t worry, just replace it with a standard header.


– the 3 wire cable don’t provide VCC to the target

only suitable for 5V design (? to be tested) edit :It works great in 3.3V, and the 3.3V built-in regulator can provide 100mA so i manage to power and get data from a EM410 GPS Module without any other component.

for a far similar dongle which provide 3.3V try the Ebay Usbflying’s dongle It’s based on the cp2102 too

for a bit-bang capability you can use a FTDI cable such as this one

for a full-featured USB-to-UART I propose you this device

and If you want even more, try the Hackaday’s Buspirate