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ATSAM4S-XPLD
331
SAM4S [DATASHEET]
11100E–ATARM–24-Jul-13
21.2.5 Device Operations
Several commands on the Flash memory are available. These commands are summarized in
.
Each command is driven by the programmer through the parallel interface running several read/write handshaking
sequences.
sequences.
When a new command is executed, the previous one is automatically achieved. Thus, chaining a read command after a
write automatically flushes the load buffer in the Flash.
write automatically flushes the load buffer in the Flash.
In the following table:
DATA[15:0] pertains to SAM4SxB/C (64/100 pins)
21.2.5.1 Flash Read Command
This command is used to read the contents of the Flash memory. The read command can start at any valid address in
the memory plane and is optimized for consecutive reads. Read handshaking can be chained; an internal address buffer
is automatically increased.
the memory plane and is optimized for consecutive reads. Read handshaking can be chained; an internal address buffer
is automatically increased.
21.2.5.2 Flash Write Command
This command is used to write the Flash contents.
The Flash memory plane is organized into several pages. Data to be written are stored in a load buffer that corresponds
to a Flash memory page. The load buffer is automatically flushed to the Flash:
to a Flash memory page. The load buffer is automatically flushed to the Flash:
Before access to any page other than the current one
When a new command is validated (MODE = CMDE)
10
Waits for NVALID high
Sets DATA bus in input mode
X
11
Sets DATA in output mode
Sets NVALID signal
Input
12
Sets NCMD signal
Waits for NCMD high
Input
13
Waits for RDY high
Sets RDY signal
Input
Table 21-5. Read Handshake (Continued)
Step
Programmer Action
Device Action
DATA I/O
Table 21-6. Read Command
Step
Handshake Sequence
MODE[3:0]
DATA[15:0]
1
Write handshaking
CMDE
READ
2
Write handshaking
ADDR0
Memory Address LSB
3
Write handshaking
ADDR1
Memory Address
4
Read handshaking
DATA
*Memory Address++
5
Read handshaking
DATA
*Memory Address++
...
...
...
...
n
Write handshaking
ADDR0
Memory Address LSB
n+1
Write handshaking
ADDR1
Memory Address
n+2
Read handshaking
DATA
*Memory Address++
n+3
Read handshaking
DATA
*Memory Address++
...
...
...
...