Hey I got my V1, awesome. I got some flat cable and connectors and I'm wondering how long I can make the flat cable before running into problems?
How do I calculate this? In our power system class, we covered inductance and admittance of 3 phase transmission lines, I'm not sure if that kind of stuff will apply here.
the shorter the better, however for most applications 20cm would be fine.
Hi Frank,
Great to hear it arrived quickly.
I would add to what sqkybeaver said - it depends on the application.
I've been doing CPLD and FPGA programming with a 30cm long tangle of 1-to-1 jumper wires, but it is quite slow.
For high-speed arm debugging or something like that short as possible is probably best, I'd try 10cm and less if possible.
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i use a debug tool with a funny wire extension, 15cm + 20cm for 8051, for the serial debugging this has rarley given me problems, made it because its the header on the boards is 1/2 the cost of a 2x10 pin header.
[quote author="ian"]Hi Frank,
Great to hear it arrived quickly.
I would add to what sqkybeaver said - it depends on the application.
I've been doing CPLD and FPGA programming with a 30cm long tangle of 1-to-1 jumper wires, but it is quite slow.
For high-speed arm debugging or something like that short as possible is probably best, I'd try 10cm and less if possible.[/quote]
It arrived fast since I paid for UPS shipping instead of regular, it actually got here in 4 days, the shipment confirmation was sent from Seeed on their Monday morning (my Sunday night), and arrived on my Monday afternoon, but the tracking said it was shipped on Friday.
Are you suggesting that the wire length actually affects the speed of the JTAG interface? Did you have to adjust the speed of the JTAG interface due to the long wires?
I made my cable about 6" long and it's then connected to an adapter I made that's designed for my target board. All the ground wires are connected.
I have a question regarding the ground wires on a 20 pin JTAG flat cable: what is the significance of having alternating signal-ground pairs of wires? Is it to provide a return path for all the signals in close proximity in order to reduce EMF?
6" should be fine. Very long wires are known to cause issues with high-speed JTAG debugging. I have not had any issues personally, but I have read horror stories on mailing lists :)
The speed of JTAG isn't effected by the wires, just that the CPLD/FPGA stuff (especially from (X)SVF) is quite a slow protocol, at least compared to JTAGing a couple flash chips and a fast microcontroller.
The alternating ground wires in the cable provide some extra noise control (assuming you use a ribbon, I only use 1:1 jumpers). It's kind of like the 80pin IDE standard that is the same as 40pin IDE, just faster with a ground between each to reduce cross talk and other issues.
Is there any cable set we can buy @seeedstudio to work with bbv2? With the best length it can work with. I had the surprise when i received my bb to see that it was not sold with a cable set to plug into the 2x10 pins header. I mean like the bus pirate set cable.
I use the female-female cables they sell and bundle them together to make my own cables. They had one with about 50 of them with 5 different colors.
like this: http://www.seeedstudio.com/depot/breadb ... -1032.html (http://www.seeedstudio.com/depot/breadboardarduino-jumper-wire-75pcs-pack-p-1032.html) buf with female-female?, can you give link?
Like those one:
http://www.sparkfun.com/products/8430 (http://www.sparkfun.com/products/8430)
?
[quote author="int0x13"]can you give link?[/quote]
Here you go: http://www.seeedstudio.com/depot/1-pin- ... th=175_187 (http://www.seeedstudio.com/depot/1-pin-dualfemale-jumper-wire-100mm-50pcs-pack-p-260.html?cPath=175_187)
exactly what i need, thank you. I was too dumb to find it myself into the store :)