On-Chip FLASH Programming Routines, Rev. 4

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Freescale Semiconductor

Routines Supported in ROM

FLASH Overview

The FLASH cell used on these 0.5-

µ MCUs is an industry-proven split-gate cell. The cell uses channel

hot electron injection for programming and Fowler-Nordheim tunnelling for erasing. All programming

With the quick byte-programming time and the organization of the FLASH array into 32-byte rows, the

entire 8-Kbyte memory can be programmed in less than one-half second. This type of FLASH is specified

to withstand at least 10,000 program/erase cycles and has enhanced reliability over previous technology.

Usually, split-gate FLASH is programmed on a row basis and erased on a page basis. Also, an entire

specified array can be mass erased. For the target MCUs, rows are 32 bytes and pages are 64 bytes (two

rows of 32 bytes each).

Routines Supported in ROM

In the ROM, six routines are supported. Because the ROM has a jump table, the user does not call the

routines with direct addresses. Therefore, the calling addresses will not change—even when the ROM

code is updated in the future.

This section introduces each routine briefly. Details are discussed in later sections.

GetByte

This routine is used to receive a byte serially on the general-purpose I/O PTA0. The receiving baud rate

is the same as the baud rate used in monitor mode. In the GetByte routine, the GetBit routine is called to

generate baud rates required for each MCU.

PutByte

This routine is used to send a byte serially on the general-purpose I/O PTA0. The sending baud rate is

the same as the baud rate specified in monitor mode.

RDVRRNG

This routine is used to perform one of two options. Using the send-out option, this routine reads FLASH

locations and sends the data out serially on the general-purpose I/O PTA0. Using to verify option, this

routine verifies the FLASH data against data in a specific RAM location, which is referred to as a DATA

array.

PRGRNGE

This routine is used to program a contiguous range of FLASH locations that is up to 32 bytes and in the

same row. Programming data is first loaded into the DATA array. PRGRNGE can be used when the