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SAM4CP [DATASHEET]
43051E–ATPL–08/14
22.4.3.2 Write Commands
Several commands are used to program the Flash.
Only 0 values can be programmed using Flash technology; 1 is the erased value. In order to program words in a page,
the page must first be erased. Commands are available to erase the full memory plane or a given number of pages. With
the EWP and EWPL commands, a page erase is done automatically before a page programming.
After programming, the page (the entire lock region) can be locked to prevent miscellaneous write or erase sequences.
The lock bit can be automatically set after page programming using WPL or EWPL commands.
Data to be programmed in the Flash must be written in an internal latch buffer before writing the programming command
in EEFC_FCR. Data can be written at their final destination address, as the latch buffer is mapped into the Flash memory
address space and wraps around within this Flash address space.
Byte and half-word AHB accesses to the latch buffer are not allowed. Only 32-bit word accesses are supported.
32-bit words must be written continuously, in either ascending or descending order. Writing the latch buffer in a random
order is not permitted. This prevents mapping a C-code structure to the latch buffer and accessing the data of the
structure in any order. It is instead recommended to fill in a C-code structure in SRAM and copy it in the latch buffer in a
continuous order.
Write operations in the latch buffer are performed with the number of wait states programmed for reading the Flash.
The latch buffer is automatically re-initialized, i.e., written with logical 1, after execution of each programming command.
The programming sequence is as follows:
1.
Write the data to be programmed in the latch buffer.
2.
Write the programming command in EEFC_FCR. This automatically clears the FRDY bit in EEFC_FSR.
3.
When Flash programming is completed, the bit EEFC_FSR.FRDY rises. If an interrupt has been enabled by set-
ting the bit EEFC_FMR.FRDY, the interrupt line of the EEFC is activated.
Three errors can be detected in EEFC_FSR after a programming sequence:
Command Error: a bad keyword has been written in EEFC_FCR.
Lock Error: the page to be programmed belongs to a locked region. A command must be run previously to unlock
the corresponding region.
Flash Error: when programming is completed, the WriteVerify test of the Flash memory has failed.
Only one page can be programmed at a time. It is possible to program all the bits of a page (full page programming) or
only some of the bits of the page (partial page programming).
Depending on the number of bits to be programmed within the page, the EEFC adapts the write operations required to
program the Flash.
Table 22-3.
Flash Descriptor Definition
Symbol
Word Index
Description
FL_ID
0
Flash Interface Description
FL_SIZE
1
Flash size in bytes
FL_PAGE_SIZE
2
Page size in bytes
FL_NB_PLANE
3
Number of planes
FL_PLANE[0]
4
Number of bytes in the first plane.
FL_NB_LOCK
4 + FL_NB_PLANE
Number of lock bits. A bit is associated with a lock region. A lock
bit is used to prevent write or erase operations in the lock region.
FL_LOCK[0]
4 + FL_NB_PLANE + 1
Number of bytes in the first lock region.