Datasheet

Table Of Contents
342
ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]
2549Q–AVR–02/2014
Figure 30-11. Serial Programming Instruction example
30.8.4 Serial Programming Characteristics
For characteristics of the Serial Programming module, see “SPI Timing Characteristics” on page 363.
Figure 30-12. Serial Programming Waveforms
30.9 Programming via the JTAG Interface
Programming through the JTAG interface requires control of the four JTAG specific pins: TCK, TMS, TDI, and
TDO. Control of the reset and clock pins is not required.
To be able to use the JTAG interface, the JTAGEN Fuse must be programmed. The device is default shipped with
the fuse programmed. In addition, the JTD bit in MCUCR must be cleared. Alternatively, if the JTD bit is set, the
external reset can be forced low. Then, the JTD bit will be cleared after two chip clocks, and the JTAG pins are
available for programming. This provides a means of using the JTAG pins as normal port pins in Running mode
Byte 1 Byte 2 Byte 3 Byte 4
Adr LSB
Bit 15 B 0
Serial Programming Instruction
Program Memory/
EEPROM Memory
Page 0
Page 1
Page 2
Page N-1
Page Buffer
Write Program Memory Page/
Write EEPROM Memory Page
Load Program Memory Page (High/Low Byte)/
Load EEPROM Memory Page (page access)
Byte 1 Byte 2 Byte 3 Byte 4
Bit 15 B 0
Adr MSB
Page Offset
Page Number
Ad
r M
MS
SB
A
A
Adr
r L
LSB
B
MSB
MSB
LSB
LSB
SERIAL CLOCK INPUT
(SCK)
SERIAL DATA INPUT
(MOSI)
(MISO)
SAMPLE
SERIAL DATA OUTPUT