280
AT90PWM216/316 [DATASHEET]
7710H–AVR–07/2013
3.
The serial programming instructions will not work if the communication is out of synchronization. When in
sync. the second byte (0x53), will echo back when issuing the third byte of the Programming Enable
instruction. Whether the echo is correct or not, all four bytes of the instruction must be transmitted. If the
0x53 did not echo back, give RESET a positive pulse and issue a new Programming Enable command.
4.
The Flash is programmed one page at a time. The memory page is loaded one byte at a time by supplying
the 6 LSB of the address and data together with the Load Program Memory Page instruction. To ensure
correct loading of the page, the data low byte must be loaded before data high byte is applied for a given
address. The Program Memory Page is stored by loading the Write Program Memory Page instruction
with the 8 MSB of the address. If polling is not used, the user must wait at least t
WD_FLASH before issuing
the next page. (See
Table 24-15.) Accessing the serial programming interface before the Flash write
operation completes can result in incorrect programming.
5.
The EEPROM array is programmed one byte at a time by supplying the address and data together with
the appropriate Write instruction. An EEPROM memory location is first automatically erased before new
data is written. If polling is not used, the user must wait at least t
WD_EEPROM before issuing the next byte.
(See
Table 24-15.) In a chip erased device, no 0xFFs in the data file(s) need to be programmed.
6.
Any memory location can be verified by using the Read instruction which returns the content at the
selected address at serial output MISO.
7.
At the end of the programming session, RESET can be set high to commence normal operation.
8.
Power-off sequence (if needed):
Set RESET to “1”.
Turn V
CC power off.
24.9.2
Data Polling Flash
When a page is being programmed into the Flash, reading an address location within the page being programmed
will give the value 0xFF. At the time the device is ready for a new page, the programmed value will read correctly.
This is used to determine when the next page can be written. Note that the entire page is written simultaneously
and any address within the page can be used for polling. Data polling of the Flash will not work for the value 0xFF,
so when programming this value, the user will have to wait for at least t
WD_FLASH before programming the next
page. As a chip-erased device contains 0xFF in all locations, programming of addresses that are meant to contain
WD_FLASH value.
24.9.3
Data Polling EEPROM
When a new byte has been written and is being programmed into EEPROM, reading the address location being
programmed will give the value 0xFF. At the time the device is ready for a new byte, the programmed value will
read correctly. This is used to determine when the next byte can be written. This will not work for the value 0xFF,
but the user should have the following in mind: As a chip-erased device contains 0xFF in all locations, program-
ming of addresses that are meant to contain 0xFF, can be skipped. This does not apply if the EEPROM is re-
programmed without chip erasing the device. In this case, data polling cannot be used for the value 0xFF, and the
user will have to wait at least t
WD_EEPROM before programming the next byte. See Table 24-15 for tWD_EEPROM value. Table 24-15. Minimum Wait Delay Before Writing the Next Flash or EEPROM Location
Symbol
Minimum Wait Delay
t
WD_FLASH
4.5 ms
tWD_EEPROM
3.6 ms
t
WD_ERASE
9.0 ms