Estimating Ap Configuration Time - Altera Cyclone IV Device Handbook

8–30
Figure 8–11
interfaces to minimize signal integrity issues.
Figure 8–11. Balanced Star Routing
Notes to
(1) Altera recommends that M does not exceed 6 inches, as listed in
(2) Altera recommends using a balanced star routing. Keep the N length equal and as short as possible to minimize
reflection noise from the transmission line. The M length is applicable for this setup.

Estimating AP Configuration Time

AP configuration time is dominated by the time it takes to transfer data from the
parallel flash to Cyclone IV E devices. This parallel interface is clocked by the
Cyclone IV E DCLK output (generated from an internal oscillator). The DCLK minimum
frequency when using the 40-MHz oscillator is 20 MHz (50 ns). In word-wide cascade
programming, the DATA[15..0] bus transfers a 16-bit word and essentially cuts
configuration time to approximately 1/16 of the AS configuration time.
and
Equation 8–4.
Size
Equation 8–5.
Cyclone IV Device Handbook,
Volume 1
Chapter 8: Configuration and Remote System Upgrades in Cyclone IV Devices
shows the recommended balanced star routing for multiple bus master
DCLK
Cyclone IV E
Master Device
Figure 8–11:
Equation 8–5 show the configuration time calculations.

maximum DCLK period

----------------------------------------------------------------

16 bits per DCLK cycle
9,600,000 bits
M (1)
Table 8–11 on page

estimated maximum configuration time
=

 
50 ns

------------- -
= 30 ms
 
16 bit
Configuration
External
Master Device
N (2)
N (2)
Micron Flash
8–28.
Equation 8–4
May 2013 Altera Corporation