Rainbow-electronics AT89C5122 Instrukcja Użytkownika Pobierz pdf (Strona 26)

AT8xC5122/23

4202E–SCR–06/06

Reset Value = XXXX 0XXXb

AT8xC5122’s CRAM and E2PROM Versions

The AT8xC5122’s CRAM and E2PROM versions implements :

- 32 KB of ROM mapped from 8000 to FFFF in which is embedded a bootloader for In-

System Programming feature

- 32 KB of CRAM (Code RAM) , a volatile program memory mapped from 0000 to 7FFF

In CRAM versions only :

- 512 bytes of E2PROM can be optionally implemented to store permanent data

In E2PROM version :

- 32KB of E2PROM are implemented to store permanent code

Warnings :

– some bytes of user program memory space are reserved for bootloader

configuration. Depending on the configuration, up to 256 bytes of code may

be not available for the user code from 7F00h location. Refer to bootloader

datasheet for further details.

– Port P3.7 may be used by the bootloader as a hardware condition at reset to

select the In-System Programming mode. Once the bootloader has started,

the P3.7 Port is no more used.

Table 8. CRAM Configuration Register - RCON (D1h)

76543210

----RPS---

Bit

Number

Bit

Mnemonic Description

7 - 4 -

Reserved

The value read from this bit is indeterminate. Do not change these bits.

3RPS

CRAM Memory Mapping Bit

Set to map the CRAM memory during MOVX instructions

Clear to map the XRAM memory during MOVX.

This bit has priority over the EXTRAM bit.

2-0 -

Reserved

The value read from this bit is indeterminate. Do not change these bits.

1 2 ... 21 22 23 24 25 26 27 28 29 30 31 ... 212 213

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Rainbow-electronics AT89C5122 Instrukcja Użytkownika Strona 26