AVR Freaks

indeed, thats a useful tip, thanks.

Welcome, hope it helps.

I always had this problem with AS7 device pack....dunno why its not working, It keeps saying "Update available" even after I update to the latest version..

I suspect the issue is like this, so they have different teams for documentation of datasheets, this is done by outsourcing to another company maybe. While the appnote is mostly written by highly expert engineers from Atmel/MC themselves. so thats why the quality is different.

Maybe you can give a look at this Application note:

Writing to Flash and EEPROM on the tinyAVR 1-series

Example code from START:

https://start.atmel.com/#applica...

In the example try to check the doxygen files for the NVMCTRL, it might help you as well. I found this information there:

The **NVMCTRL Basic** driver provides basic NVM programming functionality,
that is:
- Read and write to EEPROM
- Read and write to Flash

The NVMCTRL Basic driver has two modes of operation:
- Blocking (polled) writing to EEPROM
- Non-blocking (interrupt-driven) writing to EEPROM

NVMCTRL Basic functions writing to flash are always blocking: Program 
execution waits until write has completed, regardless of writing 
to the read-while-write section or the non-read-while-write section.

\section doc_driver_nvmctrl_basic_configuration Driver Configuration

The NVMCTRL Basic driver is configured using START. The user can 
choose from the two modes of EEPROM operation (polled/IRQ).
START also allows the user to select other device-dependent features 
such as setting Boot Lock bits etc.

START allows the user to select whether or not to place Flash functions 
in a separate segment. Some devices (e.g. Mega328PB) require the Flash 
write functions to be located in a section separate from the section 
being written. For these devices, the Flash write function should be 
located in the *Boot Loader Section (BLS)*, while the data being programmed 
should be in the *Application Section*. By placing flash write functions
in a separate segment, it is easy to locate this segment in the BLS.
The size of the BLS is device-dependent, and can often be controlled 
by fuses (typically called BOOTSZ), see the device datasheet.

By ticking the "Place Flash Functions in Separate Segment" check box 
in START, all Flash write functions are placed in a segment called:

- For the GCC compiler: .bootloader       
- For the IAR compiler: BOOTLOADER_SEGMENT

For the GCC compiler, the segment must be given a location in the 
linker file or Toolchain->AVR/GNU Linker->Memory Settings in STUDIO. 
Example: For a device with 32kb flash and 512 bytes BLS, write
*.bootloader=0x3f00* in the *FLASH segment* box in Memory Settings 
in STUDIO.

For the IAR compiler, the segment must be described in the linker file.
Example: For a device with 32kb flash and 512 bytes BLS, add
*-Z(CODE)BOOTLOADER_SEGMENT=7e00-7FFF* to the linker file


\section doc_driver_nvmctrl_basic_functional Functional Description


\subsection doc_driver_nvmctrl_basic_polled Blocking/Polled EEPROM write

In this mode, EEPROM writes of a byte or a block is performed in
a blocking way, the write function does not return until all bytes 
have been written.


\subsection doc_driver_nvmctrl_basic_sync Non-blocking/IRQ-driven EEPROM write

In this mode, EEPROM writes of a byte or a block are performed by an ISR.
The ISR is called whenever the EEPROM is ready for another EEPROM write.
The EEPROM byte or block write function returns immediately after setting
up the data structures necessary for controlling the ISR. The application
can then proceed to do other things (or go to sleep) while the EEPROM 
write is being performed. A polling function <component_name>_is_EEPROM_ready() 
is provided to check when the EEPROM write has completed.

If an EEPROM write-function is called before the previous EEPROM 
write-function has completed, the newest EEPROM write function will block 
until the previous write has completed.

If an EEPROM read-function is called before the previous EEPROM 
write-function has completed, the EEPROM read function will block 
until the previous write has completed.

If the driver is configured to be Non-blocking, a function 
<component_name>_register_callback() is provided. This function allows 
registering a callback function to be called when all EEPROM writes 
triggered by a call to an EEPROM write command have completed.


\subsection doc_driver_nvmctrl_basic_flash Flash write

All Flash write functions are blocking: They don't return until the 
operation has completed. All Flash read and write functions address 
the Flash using byte addresses.

There may be device-dependent limitations on where the Flash write functions 
may be located in Flash, see \ref doc_driver_nvmctrl_basic_configuration.
In most devices, reading the Flash while it is being programmed will cause 
instruction execution to freeze until the write has completed. This will 
impact interrupt resonse time during Flash programming to the Application 
Section, since the interrupt vectors are located in the Application Section. 

Most flash write functions have an input parameter *uint8_t *ram_buffer*.
This is a pointer to a buffer in RAM that must be at least as large as 
a Flash page. This buffer is used when doing read-modify-write operations
on flash: One Flash page is read from Flash into this buffer, then the 
buffer is modified as desired, before the Flash page is erased and 
written with the contents of the buffer. In some devices such as Tiny817
the Flash page buffer is memory mapped. In the NVMCTRL Basic driver for
these devices, the *ram_buffer* parameter is unused, but kept for API
compatibility with other devices. When calling the Flash write functions 
for these devices, the *ram_buffer* parameter is unused by the functions 
and NULL can be passed as argument when calling them.

A streaming flash write function is included, intended to be used in 
devices where a lot of data is to be written contiguously to flash, and:

- RAM resources are too limited to afford a buffer needed by the write 
  and erase page functions
- performance needs and code size concerns leaves the byte write and block 
  write functions too expensive


\section doc_driver_nvmctrl_basic_hardware Hardware Dependencies

The NVMCTRL Basic driver uses the NVM controller hardware available 
on all AVR devices. The driver does not use any I/O pins.

The configuration options in START displays options that are 
dependent on the hardware used to implement the NVMCTRL driver.
For example, an option may allow setting the Boot Lock Bit 
inhibiting writes to the BLS.


\section doc_driver_nvmctrl_basic_software Software Dependencies

The interrupt-driven configuration use the interrupt functionality 
of the underlying NVMCTRL hardware. Make sure that global interrupts 
are enabled (using sei()) and that the Interrupt Controller, if 
present, is configured so that any interrupts are serviced 
correctly.

Update for " TB3216 - Getting Started with USART ":

I guess they somehow optimized the code:

https://github.com/MicrochipTech...