Artesyn COMX-P4080-2G-ENP2 Installation and Use (August 2014) - Manual (Page 35)

Functional Description
COMX-P4080-2G-ENP2 Installation and Use (6806800P63B) 35
NAND flash. The NOR flash is used to store the RCW data, U-boot, and Linux kernel. By default,
the NAND flash is used to store the file system. There are a totally four chip-select signals
included in the local bus from CS0 to CS3. Among the CS0 to CS3, only CS0 is enabled during
power on reset. So, the chip-select-signal (CS) of the device connected to local bus from which
the system boots must be connected to CS0.
Local bus with 16 bits data bus (DQ0~DQ15) are directly routed to COM Express connectors.
A "low" state is required to enable local bus output and a "high" state or '1' is required to disable.
The following figure illustrates the distribution of local bus on P4080:
4.4 Clock
The eLBC clock is generated by platform clock. The divisor is configured by CLKDIV in Clock
Ratio Register (LCRR). The divisor is 32 when GPCM is selected as RCW source. So the eLBC
clock is platform clock / 32 = 800MHz / 32 = 25MHz.
4.5 NOR FLASH
The NOR FLASH is attached to the GPCM on local bus and works at 16-bit mode.
Figure 4-2 Distribution of Local Bus