
195
8246B–AVR–09/11
ATtiny2313A/4313
21.3.1
Pin Mapping
The pin mapping is listed in
Table 21-7. Note that not all parts use the SPI pins dedicated for the
internal SPI interface.
21.3.2
Programming Algorithm
When writing serial data to the ATtiny2313A/4313, data is clocked on the rising edge of SCK.
When reading data from the ATtiny2313A/4313, data is clocked on the falling edge of SCK. See
To program and verify the ATtiny2313A/4313 in the serial programming mode, the following
1.
Power-up sequence: apply power between V
CC and GND while RESET and SCK are
set to “0”
– In some systems, the programmer can not guarantee that SCK is held low during
power-up. In this case, RESET must be given a positive pulse after SCK has been
set to '0'. The duration of the pulse must be at least t
RST plus two CPU clock cycles.
t
RST
2.
Wait for at least 20 ms and then enable serial programming by sending the Program-
ming Enable serial instruction to the MOSI pin
3.
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
– Regardless if 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 4 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 6 MSB of the address
– If polling (RDY/BSY) is not used, the user must wait at least t
WD_FLASH before issuing
interface before the Flash write operation completes can result in incorrect
programming.
5.
The EEPROM can be programmed one byte or one page at a time.
Table 21-7.
Pin Mapping Serial Programming
Symbol
Pins
I/O
Description
MOSI
PB5
I
Serial Data in
MISO
PB6
O
Serial Data out
SCK
PB7
I
Serial Clock