Feb 7, 2014

DIY AVR Programming dongle using TTL-RS232C Converter Kit

e-Gizmo TTL to RS232 converter kit is one must-have tool if you work often on microcontroller circuits that requires connections to external RS-232C devices, such as a PC. This kit is just not a RS-232C converter, with the installation of a jumper and a suitable cable, it can be used as well as a programming dongle for early variants of Zilog Encore! microcontroller devices.

A programming dongle for the Atmel AVR series MCUs can be built just as easily using the same TTL to RS232C Converter kit. All you have to do is to build a cable assembly that will reroute the signals coming from the converter into a pin-out arrangement widely used by AVR based modules.

Materials Needed

1. 6-wire ribbon cable, 10 cm to 30 cm long.
2. 2×3 Female Header
3. 2×5 Female Header

Obtaining the headers turned out to the challenge. These headers proved to be very hard to find from the local electronics shop, that I find it much easier to acquire long (i.e. 2×20) PCB mount type header, and then simply cut them to size using a sharp razor blade.

Wiring Diagram

Wire the headers as shown in the wiring schematic. Make sure the pin 1 position of both headers is clearly identified, and must be installed with due care. The TTL to RS-232 kit male headers are not keyed, hence has no way of preventing you from inserting the female header the wrong way. The same is true on the target (2×3 header) end.

Programming Software

The dongle was tested and worked well using the popular PonyProg2000 freeware programming software. Before you can use it with PonyProg, you have to inform the PonyProg the polarity of the programming lines. To do this click

Setup>Interface Setup

The I/O port setup window will appear. Click to turn on INVERT-DIN and INVERT-DOUT check boxes.

Click to turn on Serial Option, and click the PC COM port where your AVR programming cable is installed. Finally click OK, your AVR cable setup is now complete.


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