Description
The introduction of serial configuration devices with greater than 128Mb capacity such as the EPCQ256 device requires the use of a 4-byte addressing mode instead of the default 3-byte addressing mode.
The ALTASMI_PARALLEL megafunction has an additional input signal, en4b_addr for this purpose when generated for a configuration device with greater than 128Mb capacity.
To change from 3-byte addressing mode to 4-byte addressing mode,you need to pull the write enable signal (wren) high and en4b_addr signal for at least one clock cycle. After the megafunction receives the en4b_addr command, it asserts the busy signal to indicate operation is in progress.
Figure 1 shows an example performing the change to 4-byte addressing mode.
