MC68HC908LJ12 Datasheet, PDF (65/413 Pages) Freescale Semiconductor, Inc – 8-bit microcontroller units

FLASH Memory (FLASH)
4.7 FLASH Program Operation
Programming of the FLASH memory is done on a row basis. A row
consists of 64 consecutive bytes starting from addresses $xx00, $xx40,
$xx80, or $xxC0. The procedure for programming a row of the FLASH
memory is outlined below:
1. Set the PGM bit. This configures the memory for program
operation and enables the latching of address and data for
programming.
2. Write any data to any FLASH address within the row address
range desired.
3. Wait for a time, t_nvs (10µs).
4. Set the HVEN bit.
5. Wait for a time, t_pgs (5µs).
6. Write data to the FLASH address to be programmed.
7. Wait for time, t_prog (30µs).
8. Repeat step 6 and 7 until all the bytes within the row are
programmed.
9. Clear the PGM bit.
10. Wait for time, t_nvh (5µs).
11. Clear the HVEN bit.
12. After time, t_rcv (1µs), the memory can be accessed again in read
mode.
NOTE:
This program sequence is repeated throughout the memory until all data
is programmed.
Programming and erasing of FLASH locations cannot be performed by
executing code from the FLASH memory; the code must be executed
from RAM. While these operations must be performed in the order as
shown, but other unrelated operations may occur between the steps. Do
not exceed t_prog maximum. See 23.18 FLASH Memory
Characteristics.
Figure 4-3 shows a flowchart representation for programming the
FLASH memory.
Technical Data
66
FLASH Memory (FLASH)
MC68HC908LJ12 — Rev. 2.1
Freescale Semiconductor