The Terasic MaxII Micro Kit connects to a PC via the USB bus and an onboard FTDI chip. However, it is not clear how to access the USB from the CPLD.Is there any example code around showing how to communicate to a PC via this bus?
Hello,basically all access from PC to CPLD must go through JTAG, cause only dedicated MAX II JTAG pins are connected from EPM3128 USB Blaster CPLD. This means, that the communication must utilize the sld_hub and sld_virtual_jtag Megafunctions respectively the JTAG UART core. As far as I see, Terasic has not yet included user code examples with the MAX II micro kit, only the ready-to-use ControlPanel demo. But the general virtual_jtag and JTAG UART examples should be applicable. I also noticed, that the ControlPanel communicates through the Quartus jtag_client.dll, which is undocumented to the public, as far as I know. Generally communication through Altera programming hardware isn't as open as desirable. For instance, I'm using the USB Blaster for low-level JTAG communication, accessing it directly from FTDI driver - cause the higher level is either undocumented or not conveniently accessible by user applications. Best regards, Frank
Frank,Thanks for the input. JTAG seems to be the magic word. You've given me some good pointers. I'll also be checking out other development kits that advertise USB or RS232 connectivity. -Larry
Hello Larry,it depends on your application, both required communication troughput and what kind of client connecting at the PC side. To my opinion, an open communication example, including demo client software and e. g. a library definition for the alt_jtaglib.dll utilized by DEN_Control_panel is missing. If Terasic won't provide it, motivated users hopefully will. Regards, Frank