DIY AVR Emulator

JtagICE is a classic emulator. It supports the following chips: ATmega128, ATmega128L, ATmega16, ATmega162, ATmega162V, ATmega165, ATmega165V, ATmega169, ATmega169V, ATmega16L, ATmega32, ATmega323, ATmega323L, ATmega32L, ATmega64, ATmega64L.

Although it does not support newer commonly used chips such as Mega8/48/88/168, it does not detract from its practicality. We can use this JtagICE to emulate the Mega16 chip for development, and then transplant it to M8/48/88/168 after successful development. As long as you pay attention during development, transplantation will not be difficult.

Effect diagram of using veneer IC:

But one disadvantage of using veneer IC is that the chip cannot be removed (if we want to re-burn the ROM of the chip, it would be much more convenient if we can remove it). Therefore, for this activity, we recommend using Mega16 in DIP40 package. The following is a real picture made by Hongri:




There are many kinds of circuits for homemade Jtag on the Internet. Based on the collected information, Hongri designed the simplest and easiest JTAG introduced in this article. The RS232 interface is made of discrete parts, using local materials, simple and reliable. The

J1 double-row ten-pin seat of this circuit can be used as both Jtag and ISP (controlled by jumper JP1). When the JP1 jumper is short-circuited, J1 is used for ISP download, which is convenient for updating the ROM of this Jtag. When the J1 jumper is open, it is used as JTAG.


If you have a 232 chip, you can replace the discrete RS232 part above with the following circuit:

Burning file:

After making the PCB according to the above hardware, check that the welding is correct, and then you can burn it.

There are many ways to burn. One method I (armok) recommend is: remove the M16 chip from the JTAG board, put it on a common experimental board with an ISP port, use SL-ISP1.32 software, and burn the flash.rom and epprom.rom in the AVR Studio 4.10 Rom burning file in the appendix of this article directly into the Jtag ATmega16.