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Unfortunately for us end-users, Altera has not published the details of the JTAG server or USB-Blaster protocols.
This is unfortunate, as it makes it difficult to both communicate with your own designs, and impossible to integrate custom JTAG interfaces into Quartus.
The USB-Blaster protocol was reverse-engineered a while ago:
http://sourceforge.net/apps/mediawiki/urjtag/index.php?title=cable_altera_usb-blaster The FTDI DLL can be used to access a USB-Blaster device under Windows.
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As I said above, that's not my preferred solution, but will do if jtagserver protocol is undocumented.
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If you want to communicate with your logic, then you need to adhere to the SLD protocol.
This tutorial has a Tcl script (altera_jtag_to_avalon_stp.tcl) that has the details of that protocol
http://www.alterawiki.com/wiki/using_the_usb-blaster_as_an_sopc/qsys_avalon-mm_master_tutorial and shows you how you can create a TCP/IP client that interfaces with the IP via Altera's Tcl. JTAG performance tests/analysis are here
http://www.ovro.caltech.edu/~dwh/correlator/pdf/altera_jtag_to_avalon_analysis.pdf --- Quote End ---
And this one, I am afraid, is too high level.
But I'd look into it, too.
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What are you trying to do?
Cheers,
Dave
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I am trying to operated JTAG port (TAP) of non-Altera device on one of our boards. That's pretty old design, but once in a couple of years or so we still need to make few of them. Bit-banging of MCU pins via TAP is our only way for first-time programming of on-board flash.
In the past (and present) we did it by means of Altera Byte Blaster or compatible cable, accessing PC parallel port with tiny custom Windows kernel driver.
But recently our old PCs with parallel port are dying at alarming regularity; last week another one bit the dust, not many remained and non in particularly good conditions. And buying a new PC with parallel port is a task that is, probably, above the skills of our purchasing department.
So I am flirting with idea to rewrite TAP access utilities targeting newer Altera JTAG solutions. There are many USB Blasters here, in the company, and USB is not going to disappear anytime soon. So, targeting USB blaster is a path of relatively low risk. However, if we target jtagserver, then the risk will be lower yet plus we will gain OS independence.
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