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2503Q–AVR–02/11
ATmega32(L)
tion. The Chip Erase operation turns the content of every memory location in both the Program
and EEPROM arrays into $FF.
Depending on CKSEL Fuses, a valid clock must be present. The minimum low and high periods
for the serial clock (SCK) input are defined as follows:
Low:> 2 CPU clock cycles for f
ck < 12MHz, 3 CPU clock cycles for fck ≥ 12MHz
High:> 2 CPU clock cycles for f
ck < 12MHz, 3 CPU clock cycles for fck ≥ 12MHz
SPI Serial
Programming
Algorithm
When writing serial data to the ATmega32, data is clocked on the rising edge of SCK.
When reading data from the ATmega32, data is clocked on the falling edge of SCK. See
FigureTo program and verify the ATmega32 in the SPI Serial Programming mode, the following
sequence is recommended (See four byte instruction formats in
Table 115):
1.
Power-up sequence:
Apply power between V
CC and GND while RESET and SCK are set to “0”. In some sys-
tems, the programmer can not guarantee that SCK is held low during power-up. In this
case, RESET must be given a positive pulse of at least two CPU clock cycles duration
after SCK has been set to “0”.
2.
Wait for at least 20ms and enable SPI Serial Programming by sending the Programming
Enable serial instruction to pin MOSI.
3.
The SPI Serial Programming instructions will not work if the communication is out of syn-
chronization. When in sync. the second byte ($53), 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 $53 did not echo back, give RESET a
positive pulse and issue a new Programming Enable command.
4.
258). The memory page is loaded one byte at a time by supplying the 6LSB 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 8MSB of the address. If polling is not used,
the user must wait at least t
WD_FLASH before issuing the next page. (See Table 114). Accessing the SPI Serial Programming interface before the Flash write operation com-
pletes 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 114). In a chip erased device, no $FFs in the data file(s) need to be programmed.
6.
Any memory location can be verified by using the Read instruction which returns the con-
tent 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.
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 $FF. 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 writ-