
192
8008H–AVR–04/11
ATtiny48/88
Signals are described in
Table 21-3, below. Pins not listed in the table are referenced by pin
names.
Note:
VCC - 0.3V < AVCC < VCC + 0.3V, however, AVCC should always be within 4.5 – 5.5V
Pulses are assumed to be at least 250 ns, unless otherwise noted.
The XA1/XA0 pins determine the action executed when the CLKI pin is given a positive pulse.
Table 21-3.
Pin Name Mapping
Signal Name in
Programming Mode
Pin Name
I/O
Function
RDY/BSY
PD1
O
0: Device is busy programming, 1: Device is
ready for new command
OE
PD2
I
Output Enable (Active low)
WR
PD3
I
Write Pulse (Active low)
BS1
PD4
I
Byte Select 1 (“0” selects Low byte, “1” selects
High byte)
XA0
PD5
I
XTAL Action Bit 0
XA1
PD6
I
XTAL Action Bit 1
PAGEL
PD7
I
Program memory and EEPROM Data Page
Load
BS2
PC2
I
Byte Select 2 (“0” selects Low byte, “1” selects
2’nd High byte)
DATA
{PC[1:0]: PB[5:0]}
I/O
Bi-directional Data bus (Output when OE is low)
Table 21-4.
Pin Values Used to Enter Programming Mode
Pin
Symbol
Value
PAGEL
Prog_enable[3]
0
XA1
Prog_enable[2]
0
XA0
Prog_enable[1]
0
BS1
Prog_enable[0]
0
Table 21-5.
XA1 and XA0 Coding
XA1
XA0
Action when CLKI is Pulsed
0
Load Flash or EEPROM Address (High or low address byte determined by BS1).
0
1
Load Data (High or Low data byte for Flash determined by BS1).
1
0
Load Command
1
No Action, Idle