Datasheet

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ATmega169A/PA/329A/PA/649A/P/3290A/PA/6490A/P [DATASHEET]
8284E–AVR–02/2013
When reading back a software assigned pin value, a nop instruction must be inserted as indicated in Figure 14-4.
The out instruction sets the “SYNC LATCH” signal at the positive edge of the clock. In this case, the delay tpd
through the synchronizer is 1 system clock period.
Figure 14-4. Synchronization when reading a software assigned pin value.
The following code example shows how to set port B pins 0 and 1 high, 2 and 3 low, and define the port pins from
4 to 7 as input with pull-ups assigned to port pins 6 and 7. The resulting pin values are read back again, but as pre-
viously discussed, a nop instruction is included to be able to read back the value recently assigned to some of the
pins.
out PORTx, r16 nop in r17, PINx
0xFF
0x00 0xFF
SYSTEM CLK
r16
INSTRUCTIONS
SYNC LATCH
PINxn
r17
t
pd