EP4CE40 datasheet(171/488 Pages) ALTERA

171 / 488 page

Chapter 8: Configuration and Remote System Upgrades in Cyclone IV Devices

8–7

Configuration

May 2013

Altera Corporation

Cyclone IV Device Handbook,

Volume 1

You can begin reconfiguration by pulling the nCONFIG pin low. The nCONFIG pin must

be low for at least 500 ns. When nCONFIG is pulled low, the Cyclone IV device is reset.

The Cyclone IV device also pulls nSTATUS and CONF_DONE low and all I/O pins are

tri-stated. When nCONFIG returns to a logic-high level and nSTATUS is released by the

Cyclone IV device, reconfiguration begins.

Configuration Error

If an error occurs during configuration, Cyclone IV devices assert the nSTATUS signal

low, indicating a data frame error and the CONF_DONE signal stays low. If the

Auto-restart configuration after error

option (available in the Quartus II software in

the General tab of the Device and Pin Options dialog box) is turned on, the

Cyclone IV device releases nSTATUS after a reset time-out period (a maximum of

230

μs), and retries configuration. If this option is turned off, the system must monitor

nSTATUS

for errors and then pulse nCONFIG low for at least 500 ns to restart

configuration.

Initialization

In Cyclone IV devices, the initialization clock source is either the internal oscillator or

the optional CLKUSR pin. By default, the internal oscillator is the clock source for

initialization. If you use the internal oscillator, the device provides itself with enough

clock cycles for proper initialization. When using the internal oscillator, you do not

have to send additional clock cycles from an external source to the CLKUSR pin during

the initialization stage. Additionally, you can use the CLKUSR pin as a user I/O pin.

You also have the flexibility to synchronize initialization of multiple devices or to

delay initialization with the CLKUSR option. The CLKUSR pin allows you to control

when your device enters user mode for an indefinite amount of time. You can turn on

the Enable user-supplied start-up clock (CLKUSR) option in the Quartus II software

in the General tab of the Device and Pin Options dialog box. When you turn on the

Enable user supplied start-up clock option (CLKUSR)

option, the CLKUSR pin is the

initialization clock source. Supplying a clock on the CLKUSR pin does not affect the

configuration process. After the configuration data is accepted and CONF_DONE goes

high, Cyclone IV devices require 3,192 clock cycles to initialize properly and enter

user mode.

1 If you use the optional CLKUSR pin and the nCONFIG pin is pulled low to restart

configuration during device initialization, ensure that the CLKUSR pin continues to

toggle when nSTATUS is low (a maximum of 230

μs).

User Mode

An optional INIT_DONE pin is available, which signals the end of initialization and the

start of user mode with a low-to-high transition. The Enable INIT_DONE Output

option is available in the Quartus II software in the General tab of the Device and Pin

Options

dialog box. If you use the INIT_DONE pin, it is high due to an external 10-k

pull-up resistor when nCONFIG is low and during the beginning of configuration. After

the option bit to enable INIT_DONE is programmed into the device (during the first

frame of configuration data), the INIT_DONE pin goes low. When initialization is

complete, the INIT_DONE pin is released and pulled high. This low-to-high transition

signals that the device has entered user mode. In user mode, the user I/O pins

function as assigned in your design and no longer have weak pull-up resistors.

EP4CE40 Datasheet(PDF) 171 Page - Altera Corporation

EP4CE40 Datasheet(HTML) 171 Page - Altera Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL