JTAG ICE 1 alternative usage and improvement ideas

[mcuee]

Ref: #1054

From the above thread you can see that it is not difficult to build an JTAG ICE 1 clone. There are also cheap clones available from AliExpress (a bit higher cost than USBASP but not too much). Most of them are using a USB to Serial converter (say cheap CH340G or FT232RL) and then the ATmega16A. Some of them have buffer on the output side.

This discussion is to see whether there are possible improvement for the JTAG ICE 1 clone or not.

1. One idea is to have alternative FW.
   An example will be AVR910 type. The 7.3728MHz crystal is well suitable for this purpose. (JTAG connector needs to have an adpter for ISP connector).

USBASP/USBTiny type alternative FW is probably difficult as there is usually no alternative USB connector for V-USB.
STK500v2 compatible FW should be possible as well.

2. Another idea is to enhance the JTAG support. I believe it currently it supports much less features and AVR MCUs than JTAG ICE mkii. This may not be easy as it may require reverse engineering. JTAG ICE mkii clones are rare and much more expensive.

[mcuee]

I have seen a Chinese vendor (which produces the HV STK500v2 clone using either an ATmega8535 or an 8051 type MCU) has an JTAG ICE 1 clone (with ATmega16A) which double as an STK500v2 (with alternative FW and JTAG-ISP adapter).

JTAG to ISP adapter will be necessary, since for 10pin IDC connector, JTAG pin GND is actually corresponding to ISP VCC pin.

JTAG                        ISP

TCK       GND           MOSI       VCC
TDO      VTREF         NC          GND
TMS      NSRST         RST          GND
VSUPP   NTRST        SCK         GND
TDI        GND           MISO       GND

[mcuee]

Just came across an interesting discussion here from avrfreaks.
https://www.avrfreaks.net/forum/problems-solved-jtagice-mkii-clone-wwwavrvicom

Interestingly MCUzone's clone (JTAGICE mkII-CN got a clone at that time.
Ref: http://www.mcuzone.com/clonefight/

The JTAG ICE mkii clone is not cheap as it has quite some components inside and I guess it is not easy to reverse engineering the product (MCUzone claims that their verision is not a clone but their own implementation and got the endorsement from Microchip/Atmel).

The core part of our mkII-CN circuit is made of PDIUSBD12 + 74HC573 + 62C256 + ATmega64 +74HC00 (located opposite PCB)

[mcuee]

Another JTAGICE mkii clone from Waveshare is even more expensive.
https://www.waveshare.com/product/mcu-tools/debugger-programmer/avr.htm