SAM7X128_14 Datasheet, PDF (117/662 Pages) ATMEL Corporation – ARM-based Flash MCU

Table 20-5. Read Handshake
Step
Programmer Action
1
Sets MODE and DATA signals
2
Clears NCMD signal
3
Waits for RDY low
4
Sets DATA signal in tristate
5
Clears NOE signal
6
Waits for NVALID low
7
8
Reads value on DATA Bus
9
Sets NOE signal
10
Waits for NVALID high
11
Sets DATA in output mode
12
Sets NCMD signal
13
Waits for RDY high
Device Action
Waits for NCMD low
Latch MODE and DATA
Clears RDY signal
Waits for NOE Low
Sets DATA bus in output mode and outputs
the flash contents.
Clears NVALID signal
Waits for NOE high
Sets DATA bus in input mode
Sets NVALID signal
Waits for NCMD high
Sets RDY signal
DATA I/O
Input
Input
Input
Input
Tristate
Output
Output
Output
Output
X
Input
Input
Input
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 20-6. Read Command
Step Handshake Sequence
1
Write handshaking
2
Write handshaking
3
Write handshaking
4
Read handshaking
5
Read handshaking
...
...
n
Write handshaking
n+1
Write handshaking
n+2
Read handshaking
n+3
Read handshaking
...
...
MODE[3:0]
CMDE
ADDR0
ADDR1
DATA
DATA
...
ADDR0
ADDR1
DATA
DATA
...
DATA[15:0]
READ
Memory Address LSB
Memory Address
*Memory Address++
*Memory Address++
...
Memory Address LSB
Memory Address
*Memory Address++
*Memory Address++
...
SAM7X Series [DATASHEET]
6120K–ATARM–11-Feb-14
117