AN2504 Freescale Semiconductor / Motorola, AN2504 Datasheet - Page 2

• Manufacturer Part Number: AN2504
• Description: On-Chip FLASH Programming API for CodeWarrior Software
• Manufacturer: Freescale Semiconductor / Motorola

AN2504/D
FLASH Overview
ROM-Resident Routines
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On-Chip FLASH Programming API for CodeWarrior Software
The ROM-resident routines that the API manages are found on devices that do
not have enough RAM to allow for this functionality in a RAM routine. The type
of FLASH for which these routines are applicable is called split-gate FLASH
because of the type of technology used.
Split-gate FLASH has significant advantages:
The API manages four ROM-resident routines:
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Freescale Semiconductor, Inc.
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Faster programming time — It takes 30 to 40 µs to program each byte,
which translates to a little more than a quarter second of programming
time to program an entire 8-Kbyte array.
Better endurance — This type of FLASH is specified to withstand at least
10,000 program/erase cycles. Older technologies provided only about
100 program/erase cycles.
Simpler programming algorithm — The programming algorithm for split-
gate FLASH is a simple process of turning on high voltage, applying it to
the row to be programmed, then writing values to each byte to be
programmed. This differs from past technology which required an
iterative process of turning on high voltage and applying it to a page,
writing values to each byte in the page, checking all bytes for valid
values in a “margin” read condition, and then repeating the
program/verify process until all bytes are verified correctly.
Split-gate FLASH generally is programmed on a row basis and erased
on a page basis. Also, the entire array can be mass erased. A page
always contains two rows, but the size of the page can vary from one
device to another. A typical page size is 64 or 128 bytes. Before
reprogramming a byte in one row that is currently programmed with a
different value, the entire page must be erased and reprogrammed.
Refer to the applicable data sheet for the proper program and erase
procedure for this FLASH.
GETBYTE — used to serially receive a byte
RDVRRNG — used to read and verify a range of FLASH
PRGRNGE — used to program a range of FLASH
ERARNGE — used to erase a range of FLASH
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