Datasheet

117
SAM7X Series [DATASHEET]
6120K–ATARM–11-Feb-14
20.2.5 Device Operations
Several commands on the Flash memory are available. These commands are summarized in Table 20-3 on page 114.
Each command is driven by the programmer through the parallel interface running several read/write handshaking
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.
20.2.5.1 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.
Table 20-5. Read Handshake
Step Programmer Action Device Action DATA I/O
1 Sets MODE and DATA signals Waits for NCMD low Input
2 Clears NCMD signal Latch MODE and DATA Input
3 Waits for RDY low Clears RDY signal Input
4 Sets DATA signal in tristate Waits for NOE Low Input
5 Clears NOE signal Tristate
6 Waits for NVALID low
Sets DATA bus in output mode and outputs
the flash contents.
Output
7 Clears NVALID signal Output
8 Reads value on DATA Bus Waits for NOE high Output
9 Sets NOE signal Output
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 20-6. 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++
... ... ... ...