Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family
9–13
Configuration Features
1
If you want to gain control of the EPCS pins, hold the nCONFIGpin low and pull the
nCEpin 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.
Figure 9–3. Single-Device AS Configuration
V
(1)
V
(1)
CCIO
CCIO
V
(1)
CCIO
10 kΩ
10 kΩ
Serial Configuration
10 kΩ
Cyclone III Device Family
Device
nSTATUS
CONF_DONE
nCONFIG
nCE
nCEO
N.C. (3)
GND
25 Ω (6)
DATA
DCLK
nCS
DATA[0]
DCLK
nCSO (5)
ASDO (5)
ASDI
MSEL[3..0]
(4)
(2)
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-ASDIpath to control the configuration device.
(3) The nCEOpin is left unconnected or used as a user I/O pin when it does not feed the nCEpin 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 nCSOpin functions as the FLASH_NCEpin in AP mode. The ASDOpin 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.
1
1
To tri-state the configuration bus for AS configuration schemes, you must tie nCEhigh
and nCONFIGlow.
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.
August 2012 Altera Corporation
Cyclone III Device Handbook
Volume 1
ALTERA [ ALTERA CORPORATION ]
