T83C5101 Просмотр технического описания (PDF) - Atmel Corporation

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T83C5101

8-bit Low Pin Count Microcontrollers

Atmel Corporation 

Low Pin Count

Specificities

T8xC5101/02

The T8xC5101/02 family is not able to perform any external memory access, such as a

code fetch, a look-up table access (using MOVC) or a data access (using MOVX)

because traditional Port ×0 and Port 2 are not implemented. It should be noted that 2

bits of a new port 4 are available, but they are pure user outputs. On the 28 pin package,

there is also a set of 4 extra I/Os, which cannot be used for external access.

This inability to perform external memory accesses has the following consequences:

• Port 0 SFR doesn’t exist

• Port 2 SFR doesn’t exist

• Port 4 has six bits defined among which two are pure outputs for LED driving.

• Security level 4 is no longer applicable

• Code memory addresses is limited to 4000h. Accessing to any address above

3FFFh will return indeterminate value. Jumps, subroutine Calls, MOVC instructions

should be limited to a maximum address range of 3FFFh to avoid any error.

• External data memory addresses is limited to 100h. Writing to any address above

FFh will have no effect. Reading any address above FFh will return indeterminate

value. To avoid any mistake, MOVX address should be limited to a maximum

address range of FFh.

• In Rx devices, the user could disable the XRAM (for example, if he had shared

resource at the corresponding address range). As no external access is possible

with the T83/87C510x, it makes no sense to be able to disable accesses to XRAM.

Nevertheless, access to AUXR bit 1 will cause no error and any write to this bit will

have no effect.

• As there is no external access, EA, ALE, PSEN, RD and WR signals are not

implemented. So, the corresponding pins or alternate functions are removed.

• As there is no ALE, there is no need for ALE disabling. Nevertheless, access to

AUXR bit 0 will cause no error and any write to this bit will have no effect.

• Compared to the corresponding 16 KB Rx2 device, the TS80C51RB2, the following

features are removed:

– Port 0 & 2

– PCA

– Watchdog

– ONCE mode

– Power Off Flag (POF)

7

4233H–8051–02/08

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