Datasheet

366

SAM4S Series [DATASHEET]

11100F–ATARM–29-Jan-14

21.3.3 Entering Programming Mode

The following algorithm puts the device in Parallel Programming Mode:

 Apply the supplies as described in Table 21-1.

 Apply XIN clock within T

POR_RESET

if an external clock is available.

 Wait for T

POR_RESET

 Start a read or write handshaking.

Note: After reset, the device is clocked by the internal RC oscillator. Before clearing RDY signal, if an external clock ( >

32 kHz) is connected to XIN, then the device switches on the external clock. Else, XIN input is not considered. A

higher frequency on XIN speeds up the programmer handshake.

21.3.4 Programmer Handshaking

An handshake is defined for read and write operations. When the device is ready to start a new operation (RDY signal

set), the programmer starts the handshake by clearing the NCMD signal. The handshaking is achieved once NCMD

signal is high and RDY is high.

21.3.4.1 Write Handshaking

For details on the write handshaking sequence, refer to Figure 21-2 Figure 21-3 and Table 21-4.

Figure 21-2. Parallel Programming Timing, Write Sequence

0x0025 GGPB Get General Purpose NVM bit

0x0054 SSE Set Security Bit

0x0035 GSE Get Security Bit

0x001F WRAM Write Memory

0x001E GVE Get Version

Table 21-3. Command Bit Coding (Continued)

DATA[15:0] Symbol Command Executed

NCMD

RDY

NOE

NVALID

DATA[15:0]

MODE[3:0]