Intel 80C196NU, 8XC196NP, Microcontroller manual Sram, Uart, Chip Contents, Buscon, C0H

Models: Microcontroller 80C196NU 8XC196NP

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INTERFACING WITH EXTERNAL MEMORY

8XC196

CS0#

CS2#

A19:0

AD15:0

RD#

WR#

CS1#

 

 

Flash

 

SRAM

 

256K×￿16

 

8K×￿8

 

CE#

 

 

 

 

 

 

CE#

 

A18:1

A17:0

 

A12:0

 

 

 

A12:0

 

AD15:0

D15:0

 

AD7:0

 

 

 

D7:0

 

 

 

0 WS

 

0 WS

 

80000–FFFFFH

7E000–7FFFFH

 

OE#

WE#

OE#

WE#

A2:0

A2:0

82510

 

 

UART

Rxd

 

 

 

AD7:0

D7:0

 

Txd

 

 

 

 

 

 

 

 

3WS

CE# 01E00–01EFFH

A2433-03

Figure 13-5. Example System for Setting Up Chip-select Outputs

Table 13-8. BUSCONx Registers for the Example System

Chip-

 

 

 

Contents of

select

Multiplexing

Bus Width

Wait States

BUSCONx

Output

 

 

 

 

 

 

 

 

 

 

 

 

0

Demultiplexed

16 bits

0

C0H

 

 

 

 

 

1

Demultiplexed

8 bits

3

83H

 

 

 

 

 

2

Demultiplexed

8 bits

0

80H

 

 

 

 

 

The location and size of an address range are specified by the ADDRCOMx register and the ADDRMSKx register (see Figure 13-2 and Figure 13-3). The 8-Kbyte SRAM is assigned to ad- dress range 7E000–7FFFFH and uses chip-select output 2. The 12 most-significant bits of the base address (7E000H) are written to the BASE19:8 bits in the ADDRCOM2 register, which then contains 07E0H.

The address range for CS2# is 8 Kbytes or 213 bytes (n = 13). The number of bits to be set in MASK19:8 of ADDRMSK2 is 20 – n = 7. After the 7 most-significant bits of MASK19:8 are set, ADDRMSK2 contains 0FE0H. Results for CS0# and CS1# are found similarly (see Table 13-9).

13-13

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Intel 80C196NU, 8XC196NP, Microcontroller manual Sram, Uart, Chip Contents, Buscon, C0H