321
8025I–AVR–02/09
ATmega48P/88P/168P/328P
26.6
SPI Timing Characteristics
for details.
Note:
1. In SPI Programming mode the minimum SCK high/low period is:
- 2 t
CLCL
for f
CK
< 12 MHz
- 3 t
CLCL
for f
CK
> 12 MHz
2. All DC Characteristics contained in this datasheet are based on simulation and characteriza-
tion of other AVR microcontrollers manufactured in the same process technology. These
values are preliminary values representing design targets, and will be updated after character-
ization of actual silicon.
Table 26-5.
SPI Timing Parameters
Description
Mode
Min
Typ
Max
1
SCK period
Master
ns
2
SCK high/low
Master
50% duty cycle
3
Rise/Fall time
Master
3.6
4
Setup
Master
10
5
Hold
Master
10
6
Out to SCK
Master
0.5 • t
sck
7
SCK to out
Master
10
8
SCK to out high
Master
10
9
SS low to out
Slave
15
10
SCK period
Slave
4 • t
ck
11
SCK high/low
Slave
2 • t
ck
12
Rise/Fall time
Slave
1600
13
Setup
Slave
10
14
Hold
Slave
t
ck
15
SCK to out
Slave
15
16
SCK to SS high
Slave
20
17
SS high to tri-state
Slave
10
18
SS low to SCK
Slave
20