Configuration Handbook - Kamami.pl

Configuring Mercury, APEX 20K (2.5 V), ACEX 1K & FLEX 10K DevicesIn ACEX 1K and FLEX 10K devices, initialization can be clocked by theclock input on the DCLK pin or by the optional CLKUSR pin. By default,the clock on DCLK is the clock source for initialization. The configurationfiles created by the Quartus II and the MAX+PLUS II softwareincorporate the extra bits for proper device initialization. Therefore,sending the entire configuration file to the device is sufficient to configureand initialize the device. Driving DCLK to the device after configuration iscomplete does not affect device operation.You also have the flexibility to synchronize initialization of multipledevices by using 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. Supplying a clockon CLKUSR will not affect the configuration process. After allconfiguration data has been accepted and CONF_DONE goes high,Mercury devices require 136 clock cycles to initialize properly. APEX 20Kdevices require 40 clock cycles, while ACEX 1K and FLEX 10K devicesrequire 10 clock cycles.An optional INIT_DONE pin is available, which signals the end ofinitialization and the start of user-mode with a low-to-high transition.This 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 1-kΩpull-up when nCONFIG is low and during the beginning of configuration.Once the option bit to enable INIT_DONE is programmed into the device(during the first frame of configuration data), the INIT_DONE pin will golow. When initialization is complete, the INIT_DONE pin will be releasedand pulled high. The microprocessor must be able to detect this low-tohightransition which signals the FPGA has entered user mode. In usermode,the user I/O pins will no longer have weak pull-ups and willfunction as assigned in your design. When initialization is complete, theFPGA enters user mode.To ensure DCLK and DATA0 are not left floating at the end ofconfiguration, the microprocessor must take care to drive them eitherhigh or low, whichever is convenient on your board. The DATA[7..1]pins are available as user I/O pins after configuration. When the PPSscheme is chosen in the Quartus II software, as a default these I/O pinsare tri-stated in user mode and should be driven by the microprocessor.To change this default option in the Quartus II software, select the Dual-Purpose Pins tab of the Device & Pin Options dialog box.Altera Corporation 8–37August 2005 Configuration Handbook, Volume 1