CDPCLK4 datasheet(171/274 Pages) ALTERA

171 / 274 page

Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family

9–13

Configuration Features

August 2012

Altera Corporation

Cyclone III Device Handbook

Volume 1

1 If you want to gain control of the EPCS pins, hold the nCONFIG pin low and pull the

nCE

pin high to cause the device to reset and tri-state the AS configuration pins.

Single-Device AS Configuration

The four-pin interface of serial configuration devices consists of the following pins:

■

Serial clock input (DCLK)

■

Serial data output (DATA)

■

AS data input (ASDI)

■

Active-low chip select (nCS)

This four-pin interface connects to Cyclone III device family pins, as shown in

Figure 9–3.

1 To tri-state the configuration bus for AS configuration schemes, you must tie nCE high

and nCONFIG low.

1 When connecting a serial configuration device to a Cyclone III device family in the

single-device AS configuration, you must connect a 25- series resistor at the near

end of the serial configuration device for DATA[0]. The 25- resistor in the series

works to minimize the driver impedance mismatch with the board trace and reduce

overshoot seen at the Cyclone III device family DATA[0]input pin.

Figure 9–3. Single-Device AS Configuration

Notes to Figure 9–3:

(1) Connect the pull-up resistors to the VCCIO supply of the bank in which the pin resides.

(2) Cyclone III device family uses the ASDO-to-ASDI path to control the configuration device.

(3) The nCEO pin is left unconnected or used as a user I/O pin when it does not feed the nCE pin of another device.

(4) The MSEL pin settings vary for different configuration voltage standards and POR time. To connect MSEL[3..0],

refer to Table 9–7 on page 9–11. Connect the MSEL pins directly to VCCA or GND.

(5) These are dual-purpose I/O pins. The nCSO pin functions as the FLASH_NCE pin in AP mode. The ASDO pin functions

as the DATA[1] pin in other AP and FPP modes.

(6) Connect the series resistor at the near end of the serial configuration device.

nSTATUS

nCONFIG

CONF_DONE

nCE

DATA[0]

DCLK

nCSO (5)

ASDO (5)

nCEO

MSEL[3..0]

DATA

DCLK

nCS

ASDI

VCCIO (1)

GND

10 k

VCCIO (1)

10 k

VCCIO (1)

10 k

N.C. (3)

(4)

(2)

Ω (6)

Serial Configuration

Device

Cyclone III Device Family

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