Datasheet

Figure 28-14. Virtual Flash Page Read Register
TDI
TDO
D
A
T
A
Flash
EEPROM
Fuse s
Lock Bits
STROBES
ADDRESS
Sta te
ma chine
28.10.13. Programming Algorithm
All references below of type “1a”, “1b”, and so on, refer to Table 28-20.
28.10.14. Entering Programming Mode
1. Enter JTAG instruction AVR_RESET and shift 1 in the Reset Register.
2. Enter instruction PROG_ENABLE and shift 1010_0011_0111_0000 in the Programming Enable
Register.
28.10.15. Leaving Programming Mode
1. Enter JTAG instruction PROG_COMMANDS.
2. Disable all programming instructions by using no operation instruction 11a.
3. Enter instruction PROG_ENABLE and shift 0000_0000_0000_0000 in the programming Enable
Register.
4. Enter JTAG instruction AVR_RESET and shift 0 in the Reset Register.
28.10.16. Performing Chip Erase
1. Enter JTAG instruction PROG_COMMANDS.
2. Start chip erase using programming instruction 1a.
3. Poll for chip erase complete using programming instruction 1b, or wait for t
WLRH_CE
(refer to table
Command Byte Bit Coding in section Parallel Programming Parameters, Pin Mapping, and
Commands).
28.10.17. Programming the Flash
Before programming the Flash a Chip Erase must be performed. See Performing Chip Erase.
1. Enter JTAG instruction PROG_COMMANDS.
2. Enable Flash write using programming instruction 2a.
3. Load address high byte using programming instruction 2b.
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
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