CS7808 datasheet(42/52 Pages) CIRRUS

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CS7808

6.4

ROM/NVRAM Interface

This is the interface to the non-volatile memory that contains the firmware. See Table 19. It could be either

ROM, NVRAM – FLASH, or EEPROM, or any combination of these types of memory. This interface can

also connect to SRAM that would emulate a ROM on a development system. The bus width is 8 or 16 bits.

Except for the NVM_WE_N and NVM_OE_N pins, all these pins are shared with the DRAM interface,

which operates simultaneously with the ROM/NVRAM interface.

Signal Name

Type

Description

60, 56, 54, 49,

46, 44, 40, 33,

37, 42, 45, 48,

51, 55, 59. 62

M_D[15..0]

Memory Data Bus. Use M_D[7:0] for 8-bit interface

2, 3, 5, 6, 7, 9,

10, 11, 13, 14,

15, 16

M_A[11..0]

Memory Address Bus[11..0]

74, 71, 68, 64,

67, 70, 72, 75,

78, 80, 86, 88

M_D[27..16]

Memory Address Bus[23..12]

For

16-bit data mode, M_D[26:16] is upper word address.

For 8-bit data mode, M_D[27:16] is upper byte address.

M_D[30]

Address decode low. Copy of address MSB.

M_D[31]

Address decode high. Compliment of address MSB.

NVM_WE_N

NVRAM Write Enable.

NVM_OE_N

ROM/NVRAM Output Enable.

Table 19. ROM/NVRAM Interface

CS7808 Datasheet(PDF) 42 Page - Cirrus Logic