ATtiny43U datasheet(152/182 Pages) ATMEL

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152

8048B–AVR–03/09

ATtiny43U

19.7.1

Serial Programming Algorithm

When writing serial data to the ATtiny43U, data is clocked on the rising edge of SCK.

When reading data from the ATtiny43U, data is clocked on the falling edge of SCK. See Figure

20-6 and Figure 20-7 for timing details.

To program and verify the ATtiny43U in the Serial Programming mode, the following sequence

is recommended (see four byte instruction formats in Table 19-16):

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”.

Wait for at least 20 ms and enable serial programming by sending the Programming

Enable serial instruction to pin MOSI.

The serial programming instructions will not work if the communication is out of syn-

chronization. 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.

The Flash is programmed one page at a time. The memory page is loaded one byte at

a time by supplying the 5 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 3 MSB

of the address. If polling (RDY/BSY) is not used, the user must wait at least t

WD_FLASH

before issuing the next page. (See Table 19-15 on page 153.) Accessing the serial pro-

gramming interface before the Flash write operation completes can result in incorrect

programming.

A: 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 (RDY/BSY) is not used,

the user must wait at least t

WD_EEPROM before issuing the next byte. (See Table 19-15 on

page 153.) In a chip erased device, no 0xFFs in the data file(s) need to be pro-

grammed.

B: The EEPROM array is programmed one page at a time. The Memory page is loaded

one byte at a time by supplying the 2 LSB of the address and data together with the

Load EEPROM Memory Page instruction. The EEPROM Memory Page is stored by

loading the Write EEPROM Memory Page Instruction with the 4 MSB of the address.

When using EEPROM page access only byte locations loaded with the Load EEPROM

Memory Page instruction is altered. The remaining locations remain unchanged. If poll-

ing (RDY/BSY) is not used, the used must wait at least t

WD_EEPROM before issuing the

next page (See Table 19-15 on page 153). In a chip erased device, no 0xFF in the data

file(s) need to be programmed.

Any memory location can be verified by using the Read instruction which returns the

content at the selected address at serial output MISO.

At the end of the programming session, RESET can be set high to commence normal

operation.

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