Datasheet

Note:
1. V
BOT
may be below nominal minimum operating voltage for some devices. For devices where this
is the case, the device is tested down to V
CC
= V
BOT
during the production test. This guarantees
that a Brown-Out Reset will occur before V
CC
drops to a voltage where correct operation of the
microcontroller is no longer guaranteed. The test is performed using BODLEVEL = 110 and 101 .
29.6. External interrupts characteristics
Table 29-8. Asynchronous external interrupt characteristics.
Symbol Parameter Min. Typ. Max. Units
t
INT
Minimum pulse
width for
asynchronous
external
interrupt
- 50 - ns
29.7. SPI Timing Characteristics
Table 29-9. SPI Timing Parameters
Description Mode Min. Typ Max Units
SCK period Master - See Table. Relationship Between SCK and the
Oscillator Frequency in "SPCR – SPI Control Register"
- ns
SCK high/low Master - 50% duty cycle -
Rise/Fall time Master - 3.6 -
Setup Master - 10 -
Hold Master - 10 -
Out to SCK Master - 0.5 • t
sck
-
SCK to out Master - 10 -
SCK to out high Master - 10 -
SS low to out Slave - 15 -
SCK period Slave 4 • t
ck
- -
SCK high/low
(1)
Slave 2 • t
ck
- -
Rise/Fall time Slave - - 1600
Setup Slave 10 - -
Hold Slave t
ck
- -
SCK to out Slave - 15 -
SCK to SS high Slave 20 - -
SS high to tri-state Slave - 10 -
SS low to SCK Slave 2 • t
ck
- -
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
400