Altera Corporation
7
Configuration Devices for SRAM-Based LUT Devices Data Sheet
Device
Configuration
The control signals for configuration devices—nCS, OE, and DCLK—
interface directly with APEX II, APEX 20K, Mercury, ACEX 1K, and FLEX
device control signals. All APEX II, APEX 20K, Mercury, ACEX 1K, and
FLEX devices can be configured by a configuration device without
requiring an external intelligent controller.
The configuration device’s OE and nCS pins control the tri-state buffer on
the DATA output pin, and enable the address counter (and the oscillator in
EPC4, EPC 8, EPC16, EPC2, EPC1, and EPC1441 devices). When OE is
driven low, the configuration device resets the address counter and tri-
states its DATA pin. The nCS pin controls the output of the configuration
device. If nCS is held high after the OE reset pulse, the counter is disabled
and the DATA output pin is tri-stated. When nCS is driven low, the counter
and DATA output pin are enabled. When OE is driven low again, the
address counter is reset and the DATA output pin is tri-stated, regardless
of the state of nCS.
1
The EPC4, EPC8, EPC16, EPC2, EPC1, and EPC1441 devices
determine the operation mode and whether the APEX 20K,
Mercury, ACEX 1K, FLEX 10K, FLEX 8000, or FLEX 6000
protocols should be used when OE is driven high.
When the configuration device has driven out all of its data and has
driven nCASC low, the device tri-states the DATA pin to avoid contention
with other configuration devices.
The EPC2 device allows the user to initiate configuration of the PLD via
an additional pin, nINIT_CONF, that can be tied to the nCONFIG pin of the
PLD(s) to be configured. A JTAG instruction causes the EPC4, EPC8,
EPC16, and EPC2 device to drive nINIT_CONF low, which in turn pulls
nCONFIG
low. The EPC4, EPC8, EPC16, and EPC2 device then drives
nINIT_CONF
high to start configuration. When the JTAG state machine
exits this state, nINIT_CONF releases nCONFIG and configuration is
initiated.
1
An EPC4, EPC8, EPC16, and EPC2 device can be programmed
with a POF generated for an EPC1 or EPC1441 device, however,
an EPC2 device cannot configure FLEX 6000 or FLEX 8000
devices. An EPC1 device can be programmed using a POF
generated for an EPC1441 device.
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