ATMEGA64M1-15MZ Atmel, ATMEGA64M1-15MZ Datasheet - Page 280

• Manufacturer Part Number: ATMEGA64M1-15MZ
• Description: MCU AVR 64KB FLASH 3PSC 32-VQFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA64M1-15MZ

• Package / Case: 32-VQFN
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Speed: 16MHz
• Eeprom Size: 2K x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Program Memory Size: 64KB (64K x 8)
• Data Converters: A/D 11x10b; D/A 1x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Connectivity: CAN, LIN, SPI, UART/USART
• Core Size: 8-Bit
• Processor Series: ATMEGA64x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT, ATADAPCAN01
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Lead Free Status / Rohs Status: Details

24.3
24.3.1
24.3.2
280
Read-While-Write and No Read-While-Write Flash Sections
Atmel ATmega16/32/64/M1/C1
RWW – Read-While-Write Section
NRWW – No Read-While-Write Section
Whether the CPU supports Read-While-Write or if the CPU is halted during a Boot Loader
software update is dependent on which address that is being programmed. In addition to the
two sections that are configurable by the BOOTSZ Fuses as described above, the Flash is
also divided into two fixed sections, the Read-While-Write (RWW) section and the No
Read-While-Write (NRWW) section. The limit between the RWW- and NRWW sections is
given in
the two sections is:
Note that the user software can never read any code that is located inside the RWW section
during a Boot Loader software operation. The syntax “Read-While-Write section” refers to
which section that is being programmed (erased or written), not which section that actually is
being read during a Boot Loader software update.
If a Boot Loader software update is programming a page inside the RWW section, it is possi-
ble to read code from the Flash, but only code that is located in the NRWW section. During an
on-going programming, the software must ensure that the RWW section never is being read. If
the user software is trying to read code that is located inside the RWW section (i.e., by a
call/jmp/lpm or an interrupt) during programming, the software might end up in an unknown
state. To avoid this, the interrupts should either be disabled or moved to the Boot Loader sec-
tion. The Boot Loader section is always located in the NRWW section. The RWW Section
Busy bit (RWWSB) in the Store Program Memory Control and Status Register (SPMCSR) will
be read as logical one as long as the RWW section is blocked for reading. After a program-
ming is completed, the RWWSB must be cleared by software before reading code located in
the RWW section.
page 284.
The code located in the NRWW section can be read when the Boot Loader software is updat-
ing a page in the RWW section. When the Boot Loader code updates the NRWW section, the
CPU is halted during the entire Page Erase or Page Write operation.
Table 24-1.
• When erasing or writing a page located inside the RWW section, the NRWW section can
• When erasing or writing a page located inside the NRWW section, the CPU is halted during
Which Section does the Z-pointer
be read during the operation.
the entire operation.
Table 24-8 on page 292
Address During the
for details on how to clear RWWSB.
Programming?
NRWW Section
RWW Section
Read-While-Write Features
See “Store Program Memory Control and Status Register – SPMCSR” on
and
Figure 24-2 on page
Which Section Can
be Read During
Programming?
NRWW Section
None
282. The main difference between
Is the CPU
Halted?
Yes
No
Read-While-Write
Supported?
7647G–AVR–09/11
Yes
No