XDS100 USB JTAG Emulator

Hi,

Aren't EMU pins driven with open collector and then pull-upped on procesor side ? I think that 74HC03D is OC version of 74HC00.

I implemented XDS100 clone by myself. But I remove support for EMU0 and EMU1 because I will not use it. I added isolation to remove ground loops.

Here is the schematics http://zmatkar.k25.cz/sdileni/CCS-XDS100/JTAG_v3-1.png

T.K.

Hi Thomas,

Thanks for the reference schematic.

What's the impact of eliminating EMU0/1? Can we debug the target properly without these lines? What targets you have tried? mine is F2812. How's the XDS100 clone that you made while debugging the target? Is it smooth?

-Regards, Sinoj

I use F2812 too. EMU pins are used to power on halt etc., but I think that F2812 doesn't support this modes, so I decided to remove EMU drivers - this saves one isolater. Nothing bad happened and JTAG emulator work as excepted.

Debugging with XDS100 have acceptable performance, but lower than XDS5XX. Take a look at pages about XDS100, everything

If you understand czech language, I can send you short paper about my XDS100 clone.

T.

Hi,

I think your schematic is much simpler than that I found in the TI web.

Some doubts:

1. How to achieve EMU0/EMU1 w.r.t your schematic? || FT2232 -> ISOLATOR -> Target || will do right, as like, TDI, TCK and TMS? Any extra circuit needed?

2. Will the schematic support 1V8 devices?

I do not know Czech. But if its in rich text I can translate. Please disclose the document.

-SBS

Ad 1: reimplementing EMU pins should be a bit hard. First thing is, that EMU pins must be open collector. It means you can't use ADuM1200 for isolating, but 6N137 or similar do the job well. By the way, 6N137 can replace ADuM at all positions. On the other way, 6N137 is optocoupler with LED on input so you must add resistor to limit current etc ... If you look to original schematic, there is also NAND gates (74HC03) and pin GPIOL1 and OE controls them. You should implement this logic too.

Ad 2: Schematics with ADuM1200 can support only 2,7-5V. This is limitation of ADuM1200. I look at Analog Devices web and they don't offer isolator with 1,8V Ucc. I'm not sure, isn't even devices with 1V8 core 3V3 tolerant on pins ? If so, there is no problem. If not, then you can add SN74CBT3125 as level convertor.

And finally you will end with original schematics :)

Here is my paper (sorry - only pdf) http://zmatkar.k25.cz/sdileni/CCS-XDS100/prispevek.pdf

May I repeat the earlier question:

1. In the TI schematic where's 5V0 <-> 3V3 and 5V0 <-> 1V8 conversion or isolation or transceiver section? I just see 'power sequence control logic' and SN74CBTLV3125 (FET Bus Switch) -> NUP4201DR2 (Transient Voltage Suppressor) stages.

2. 81K - 20K potential divider is sourcing the supply for SN74CBTLV3125 along with output from 2V5 (Target VDD) comparator. What's the logic?

-SBS

Ad 2: comparator switches supply behind 4V and 2,2V. FET switches propably working only as an isolator, when there is no power from USB.

Ad 1: I think, that almost all IO have internal clamping diodes, so I can safely drive this pins from higher voltage - if I use serial resistor to limit current. Maybe this is not a case, because I didn't see limit resistors in schematics. But from lower voltage to higher I need level convertor - 74LVC2T45 in schematic.

T.K.

Hi,

no there isn't difference. If you program right VID and PID to JTAG-V3-1, there will be no problem with drivers used for XDS100.

One exception, driver let you set behavior of EMU pins, but they are not supported by JTAG-v3-1.

No I haven't. I will not use EMU pins, so I didn't implement HW support for them.

In any case, adding support for EMU pins should be rather easy.

Hi

I think that if we connect 16,17,19 pin of FT2232 to JTAG port(14 pin) According to the map of XDS100 ,we can solve that problem. What do you think?

Hi,

yes it can solve problem. Take care about logic and open collector output for EMU pins. Easiest way should be by using two 6N137 or similar for isolation.

By the way, I didn't find any interresting functionality of EMU pins (for F2812 CPU). Is there some reason for support them ?

Hi,

Thanks alot.

 I try to make it for our University, so it must be complete. I added three NOT gate According to XDS100 map and I use ADUM1200 for EMU0 & EMU0 pin isolation and  I removed 74HC74,  TLC393, MCP6041. I think it must be true. I want to know your opinion. what do you think? Thanks alot.

I think, that EMU pins must be an open collector, therefore you can't use ADUM1200 as an isolator. Replace ADUM with 6N137 or similar optocoupler with OC output.

I made this for our university too and there is no problem with EMU pins not used ...