Configuration Handbook - Kamami.pl

Active Serial Configuration (Serial Configuration Devices)After all configuration bits are received by the Stratix II or Stratix II GXdevice, it releases the open-drain CONF_DONE pin, which is pulled highby an external 10-kΩ resistor. Initialization begins only after theCONF_DONE signal reaches a logic high level. All AS configuration pins,DATA0, DCLK, nCSO, and ASDO, have weak internal pull-up resistors thatare always active. After configuration, these pins are set as inputtri-stated and are driven high by the weak internal pull-up resistors. TheCONF_DONE pin must have an external 10-kΩ pull-up resistor in order forthe device to initialize.In Stratix II and Stratix II GX devices, the initialization clock source iseither the 10-MHz (typical) internal oscillator (separate from the activeserial internal oscillator) or the optional CLKUSR pin. By default, theinternal oscillator is the clock source for initialization. If the internaloscillator is used, the Stratix II or Stratix II GX device provides itself withenough clock cycles for proper initialization. You also have the flexibilityto synchronize initialization of multiple devices or to delay initializationwith the CLKUSR option. The Enable user-supplied start-up clock(CLKUSR) option can be turned on in the Quartus II software from theGeneral tab of the Device & Pin Options dialog box. When you Enablethe user supplied start-up clock option, the CLKUSR pin is theinitialization clock source. Supplying a clock on CLKUSR will not affectthe configuration process. After all configuration data has been acceptedand CONF_DONE goes high, CLKUSR is enabled after 600 ns. After thistime period elapses, Stratix II and Stratix II GX devices require 299 clockcycles to initialize properly and enter user mode. Stratix II andStratix II GX devices support a CLKUSR f MAX of 100 MHz.An optional INIT_DONE pin is available, which signals the end ofinitialization and the start of user-mode with a low-to-high transition.The Enable INIT_DONE Output option is available in the Quartus IIsoftware from the General tab of the Device & Pin Options dialog box.If the INIT_DONE pin is used, it will be high due to an external 10-kΩpull-up resistor when nCONFIG is low and during the beginning ofconfiguration. Once the option bit to enable INIT_DONE is programmedinto the device (during the first frame of configuration data), theINIT_DONE pin goes low. When initialization is complete, theINIT_DONE pin is released and pulled high. This low-to-high transitionsignals that the device has entered user mode. When initialization iscomplete, the device enters user mode. In user mode, the user I/O pinsno longer have weak pull-up resistors and function as assigned in yourdesign.If an error occurs during configuration, Stratix II and Stratix II GX devicesassert the nSTATUS signal low, indicating a data frame error, and theCONF_DONE signal stays low. If the Auto-restart configuration after erroroption (available in the Quartus II software from the General tab of the7–38 Altera CorporationStratix II Device Handbook, Volume 2 May 2007