Configuration Handbook - Kamami.pl

JTAG ConfigurationMercury, APEX 20K (2.5 V), ACEX 1K, and FLEX 10K devices havededicated JTAG pins that always function as JTAG pins. JTAG testing canbe performed on Mercury, APEX 20K (2.5 V), ACEX 1K, and FLEX 10Kdevices both before and after configuration, but not during configuration.The chip-wide reset (DEV_CLRn) and chip-wide output enable (DEV_OE)pins on Mercury, APEX 20K (2.5 V), ACEX 1K, and FLEX 10K devices donot affect JTAG boundary-scan or programming operations. Togglingthese pins does not affect JTAG operations (other than the usualboundary-scan operation).When designing a board for JTAG configuration of Mercury, APEX 20K(2.5 V), ACEX 1K, and FLEX 10K devices, the dedicated configurationpins should be considered. Table 8–19 shows how these pins should beconnected during JTAG configuration.Table 8–19. Dedicated Configuration Pin Connections During JTAG ConfigurationSignalnCEnCEOMSELnCONFIGnSTATUSCONF_DONEDCLKDATA0DescriptionOn all Mercury, APEX 20K (2.5 V), ACEX 1K, and FLEX 10K devices in the chain, nCE shouldbe driven low by connecting it to ground, pulling it low via a resistor, or driving it by some controlcircuitry. For devices that are also in multi-device PS, PPS or PPA configuration chains, the nCEpins should be connected to GND during JTAG configuration or JTAG configured in the sameorder as the configuration chain.On all Mercury, APEX 20K (2.5 V), ACEX 1K, and FLEX 10K devices in the chain, nCEO can beleft floating or connected to the nCE of the next device. See nCE description above.These pins must not be left floating. These pins support whichever non-JTAG configuration isused in production. If only JTAG configuration is used, you should tie both pins to ground.Driven high by connecting to V CC , pulling high via a resistor, or driven by some control circuitry.Pull to V CC via a 1-kΩ resistor. When configuring multiple devices in the same JTAG chain, eachnSTATUS pin should be pulled up to V CC individually. nSTATUS pulling low in the middle of JTAGconfiguration indicates that an error has occurred.Pull to V CC via a 1-kΩ resistor. When configuring multiple devices in the same JTAG chain, eachCONF_DONE pin should be pulled up to V CC individually. CONF_DONE going high at the end ofJTAG configuration indicates successful configuration.Should not be left floating. Drive low or high, whichever is more convenient on your board.Should not be left floating. Drive low or high, whichever is more convenient on your board.When programming a JTAG device chain, one JTAG-compatible header isconnected to several devices. The number of devices in the JTAG chain islimited only by the drive capability of the download cable. When four ormore devices are connected in a JTAG chain, Altera recommendsbuffering the TCK, TDI, and TMS pins with an on-board buffer.8–60 Altera CorporationConfiguration Handbook, Volume 1 August 2005