ATMEGA640 datasheet(70/436 Pages) MICROCHIP

tên linh kiện	ATMEGA640

Giải thích chi tiết về linh kiện	8-bit Microcontroller with 16/32/64KB In-System Programmable Flash

PDF	436 Pages

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ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

LATCH” signal. The signal value is latched when the system clock goes low. It is clocked into the PINxn Register at

the succeeding positive clock edge. As indicated by the two arrows tpd,max and tpd,min, a single signal transition

on the pin will be delayed between ½ and 1½ system clock period depending upon the time of assertion.

When reading back a software assigned pin value, a nop instruction must be inserted as indicated in Figure 13-4.

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 one system clock period.

Figure 13-4. Synchronization when Reading a Software Assigned Pin Value

The following code example shows how to set port B pins 0 and 1 high, pins 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

previously 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

ATMEGA640 bảng dữ liệu(PDF) 70 Page - Microchip Technology