JTAG interface can not be connected

Probe domestic switch needle KG-300K needle head diameter is 3.0mm normally open switch needle

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This article contains two parts: 1) Continued to write TI DSP connection problems; 2) By the way, the XTAG port of Xilinx FPGA is not connected.

First, TI DSP is not connected?

Half a year ago, I posted a blog post titled "DSP is not connected? TMS320C6416T+seed-XDS510 PLUS" explains the reasons for the lack of multiple DSP connections. TI DSP performance is very good, but the connection problem is a big problem, recently I was bored, but after a long period of investigation, I finally solved the problem. Perhaps the cause of the problem is not the problem of the netizens. Here I just want to emphasize one thing: if your DSP system is always connected Not on, then there is definitely a problem with the hardware. In addition to the troubleshooting in the blog post "DSP is not connected? TMS320C6416T+seed-XDS510 PLUS", you must pay attention to your reset circuit, remember to remember!!!

This DSP connection has not been tossed for a long time, Debug in CCS --- Reset Emulator can be executed (if this is not an estimate is not the driver is not connected or not connected, etc.).

First paste your own reset circuit:

As shown, the reset circuit uses an ADM706TARZ chip.

In the first two weeks, I found that the DSP could not be connected. Later, I measured the two ends of the switch S1 and found that the two ends were not connected after the switch was pressed. Later, after switching a switch, the DSP could be connected.

Later, I couldn't connect anymore. What happened? It is normal to measure each pin of the DSP's JTAG interface. After power-on, each pin is also tested. Here, the voltage of each pin is normal. Post the value to make a note:

TMS————3.05V; TRST————0V; TDI————3.04V; TDO————3.16V; TCK_RET————3.03V; TCK————3.03V; EMU1—— ——3.27V; EMU2————3.27V; VCC————3.28V; GND————0V;

The multimeter DC test used in the test, because there is no oscilloscope at hand, so the multimeter will be used all at once. The DSP JTAG connection is shown below:

Everything is normal, why can't I connect? The switch has been tested several times. There is no problem in the past few days. The most depressing thing is that sometimes I can connect, sometimes I can't connect, I am a little helpless. ...

Finally, I found that sometimes I can connect more times after resetting. Is it still a reset problem?

So I measured the 7 feet of ADM706TARZ and found that it is usually low level. After pressing the reset button, it is actually about 1.2V. If it is broken, this chip is definitely broken...

So I changed my new movie and everything is fine...

Here again, I am inspired by the connection I got from this DSP:

If the DSP is not connected, it is definitely a problem with the hardware connection, please pay special attention to the problem of the reset circuit!!!

2) The JTAG port of the Xilinx FPGA cannot be connected.

The JTAG circuit of the FPGA is verified. Open the ChipScope and connect it, but now it is not connected. The JTAG of the FPGA passes through a 244 buffer chip. The circuit is as follows. The line on the right of 244 is directly connected to the corresponding pin of the FPGA. on.

Trying too many times or not connecting, I am a little desperate, and then no way, I will test the JTAG pin, and did not power on, the result is really a problem, TDO actually shorted the ground This is how it is, J10 is a single-row pin will certainly not have a problem, it can only be 244 broken, well, so I changed a SN74LVTH244ADBR, everything is OK!

My inspiration through this question is: If you can't connect, it is very likely that there is a problem with the hardware circuit!!!

OK, today's exploration is here, the road is long and it's a long way to go, I will go up and down!

I don't know if I haven't had the chance to touch these things again. I still have a kind of sadness in my heart. I wish you good luck!