Programmer Connections

Hi guys,

I am programming an ATmega644P which I found lying in my storeroom. It is in a good condition but I have a confusion about how to program it with my Arduino Mega.

Also, can I use a 24MHz crystal (I found it in the storeroom too…!!!)

I guess you can program it using Arduino as ISP or using USBAsp.

What about the connections and the speed?

SagarDev:
What about the connections and the speed?

I didnt understand your question.

How do I connect the Arduino to my ATmega?

Is 24MHz okay for the MCU?

you need to use SPI communication to bootload.

Not sure about the clock speed, I normally use 16MHz as the clock. Or for testing purpose you can use the internal clock (just for testing).

Connect like here:
http://www.gammon.com.au/breadboard
You can download and browse the code at github, see if 644x is supported.
Programmer 644
sck sck
mosi mosi
miso miso
ss (D10 on Uno) Reset
Gnd Gnd
+5 Vcc

Wiring a 644 is the same as wiring a 1284 (1284 has same pinout, but twice the memory)
and they have different Fuses.

24 MHz will certainly run the millis() and micros() and Serial rates faster, making Serial downloads difficult.
You could try changing the clock speed in boards.txt, that might work.

everyone help me!
How to slove
avrdude: usbdev_open ( ): did not find any usb device "usb"

thantzinwin

Please be in the topic

Now, if I connect the 16u2 to the 644 can I program it?

16mhz crystal with a 22pf caps to the GND in series to the crystal.

sarouje:
16mhz crystal with a 22pf caps to the GND in series to the crystal.

But the datasheet mentions 20MHz and few on google say that 24MHz is okay. Just confirming....

SagarDev:
Now, if I connect the 16u2 to the 644 can I program it?

Can I ?

Yes 20mhz is the max clock speed I guess, so you need a crystal at 20mhz.

SagarDev:
Now, if I connect the 16u2 to the 644 can I program it?

Can I ?

This depends on the fuse you used while bootloading, say you used a bootloader which configured to use 16mhz then you should use a 16mhz crystal. It's all depends on the bootloader fuses.

SagarDev:
But the datasheet mentions 20MHz

There would seem to be a hint there.

I wonder what it means?
:roll_eyes: