AT80251G2D-3CSUM(2006) View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT80251G2D-3CSUM
(Rev.:2006)

8/16-bit Microcontroller with Serial Communication Interfaces

Atmel Corporation 

Configuration Bytes

AT/TSC8x251G2D

The TSC80251G2D derivatives provide user design flexibility by configuring certain

operating features at device reset. These features fall into the following categories:

• external memory interface (Page mode, address bits, programmed wait states and

the address range for RD#, WR#, and PSEN#)

• source mode/binary mode opcodes

• selection of bytes stored on the stack by an interrupt

• mapping of the upper portion of on-chip code memory to region 00:

Two user configuration bytes UCONFIG0 (see Table 11) and UCONFIG1 (see Table

12) provide the information.

When EA# is tied to a low level, the configuration bytes are fetched from the external

address space. The TSC80251G2D derivatives reserve the top eight bytes of the mem-

ory address space (FF:FFF8h-FF:FFFFh) for an external 8-byte configuration array.

Only two bytes are actually used: UCONFIG0 at FF:FFF8h and UCONFIG1 at

FF:FFF9h.

For the mask ROM devices, configuration information is stored in on-chip memory (see

ROM Verifying). When EA# is tied to a high level, the configuration information is

retrieved from the on-chip memory instead of the external address space and there is no

restriction in the usage of the external memory.

17

4135F–8051–11/06

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