ATMEGA16U2-16AU Atmel, ATMEGA16U2-16AU Datasheet - Page 232

• Manufacturer Part Number: ATMEGA16U2-16AU
• Description: 8-bit Microcontrollers - MCU 16K Flash
• Manufacturer: Atmel

Specifications of ATMEGA16U2-16AU

• Product Category: 8-bit Microcontrollers - MCU
• Rohs: yes
• Core: AVR
• Data Bus Width: 8 bit
• Program Memory Size: 16 KB
• Data Ram Size: 1.25 KB
• Data Rom Size: 512 B
• Program Memory Type: Flash
• Factory Pack Quantity: 1250

23.7
7799D–AVR–11/10
Addressing the Flash During Self-Programming
Figure 23-3. Boot Process Description
The Z-pointer is used to address the SPM commands. The Z pointer consists of the Z-registers
ZL and ZH in the register file. The number of bits actually used is implementation dependent.
Since the Flash is organized in pages (see
be treated as having two different sections. One section, consisting of the least significant bits, is
addressing the words within a page, while the most significant bits are addressing the pages.
This is shown in
addressed independently. Therefore it is of major importance that the Boot Loader software
addresses the same page in both the Page Erase and Page Write operation. Once a program-
ming operation is initiated, the address is latched and the Z-pointer can be used for other
operations.
The (E)LPM instruction use the Z-pointer to store the address. Since this instruction addresses
the Flash byte-by-byte, also bit Z0 of the Z-pointer is used.
Reset Vector = Application Reset
Figure
BOOTRST
HWBE
23-4. Note that the Page Erase and Page Write operations are
Table 25-7 on page
ATmega8U2/16U2/32U2
PD7/HWB
RESET
Ext. Hardware
Conditions
Reset Vector =Boot Lhoader Reset
249), the Program Counter can
t
SHRH
t
HHRH
232