P89V52X2FN datasheet(35/57 Pages) NXP

35 / 57 page

P89V52X2_3

Product data sheet

Rev. 03 — 4 May 2009

35 of 57

NXP Semiconductors

P89V52X2

80C51 with 256 B RAM, 192 B data EEPROM

• Map the data EEPROM into code memory space if not already mapped.

• Write the data EEPROM byte address into the DPTR.

• Use the MOVC instruction to read the data EEPROM.

6.13.5 Erasing a complete page (64 B)

A complete page can be erased by performing the following sequence:

• Map the data EEPROM into code memory space if not already mapped.

• Write the lower 8-bits of the data EEPROM page’s start address into FMADRL.

• Write the ERS_DP command (33H) to FMCON.

Once the ERS_DP command is written to FMCON, code execution will stall until the

operation is completed, approximately 6 ms.

6.13.6 Data EEPROM programming and erasing using the page register

In addition to page erase, a 64 B page register is included which allows from 1 B to 64 B

of a given page to be programmed or erase/programmed at the same time, substantially

reducing overall programming time. Two programming operations are provided:

• Program only operation. This operation used the PROG (48H) command and

programs the contents of the page register into the data EEPROM page. This

operation requires that the bytes being programmed have been previously erased.

This operation requires approximately 2 ms to complete.

• Erase and Program operation. This operation uses the EP (68H) command to both

erase and program the bytes previously loaded into the page register. This command

is often useful to erase and reprogram a single byte of data. This operation requires

approximately 4 ms to complete.

The page register consists of 64 B and an update ﬂag for each byte. When a LOAD

command is issued to FMCON the page register contents and all of the update ﬂags will

be cleared. When FMDATA is written, the value written to FMDATA will be stored in the

page register at the location speciﬁed by the lower 6 bits of FMADRL. In addition, the

update ﬂag for that location will be set. FMADRL will auto-increment to the next location.

Auto-increment after writing to the last byte in the page register will ‘wrap-around’ to the

ﬁrst byte in the page register, but will not affect FMADRL[7:6]. Bytes loaded into the page

location in the page register can only be written once following each LOAD command.

Attempts to write to a page register location more than once should be avoided.

FMADRH and FMADRL[7:6] are used to specify a page in the code memory space. When

the PROG command is written to FMCON, the locations within the data EEPROM page

that correspond to updated locations in the page register will have their contents

programmed with the contents of their corresponding locations in the page register. Only

the bytes that were loaded into the page register will be programmed in the data EEPROM

array. Other bytes within the data EEPROM array will not be affected. The EP command

works similarly except that If the EP command is written, the corresponding bytes in the

data EEPROM will be erased prior to being programmed. This is often useful for erasing

and programming a small number of bytes or even a single byte.

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