Cypress FM4 Series - Page 818

CHAPTER 14: External Bus Interface
818 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
Setup Example
ADDR = 0b0001_0000 ([27:20] of the first MCSX address. 0x6100_0000 in this setup.)
MASK = 0b000_0011 (Mask bits [26:20] for MCSX. Address area for this setup: 4MB.)
Select an area size with the mask setup values.
In the example, setup range 0x6100_0000 to 0x613F_FFFF (4MB) will be selected.
ADDR&(!MASK) = 0b0001_0000
− Device to be selected
When the internal bus address (address for external I/F) AD = 0x6101_1000:
0x6101_1000 -> 0b0110_0001_0000_0001_0001_0000_0000_0000
AD[27:20] => 0b0001_0000
Masking comparison
ADDR & (!MASK) = 0b0001_0000
AD [27:20] & (!MASK) = 0b0001_0000 ….. Matched. A device will be selected.
− Device not to be selected
When the internal bus address (address for external I/F) AD = 0x60C0_0000:
0x60C0_0000 -> 0b0110_0000_1100_0000_0000_0000_0000_0000
AD[27:20] => 0b0000_1100
Masking comparison
ADDR & (!MASK) = 0b0001_0000
AD [27:20] & (!MASK) = 0b0000_1100 …..Unmatched. No device will be selected.