I want to make my own project using the ATmega 1280 running at 3.3V and 8Mhz. I have already made the circuit for the processor to run (in eagle) and now I just need to figure out how to run it. Here are the processes I've been reading about, but I wanted to get everyone's opinion on which one is better or if there is an easier/better one.
Program using another arduino via ISP. I've read about this and it looks pretty straightforward using the 328 but I have yet to see a guide that makes it possible with the 1280. I'm sure some pins are changed, and maybe fuses are in different locations.
Burn the bootloader onto the 1280 and using FTDI to program it. I like this option the best, but I have absolutely no idea how to go about doing it.
Are there better options? Thanks!
Put a bootloader on it and program using an FTDI cable. Information here:
And here (shows a 1284):
1280 existed as a real Arduino product, you should be able to use existing bootloader and just change clock frequency in boards.txt.
I don't like fooling with Arduino's as ISPs, if you're doing more projects than get a dedicated tool - I used Atmel AVR ISP MKii to install bootloaders. As purchased, it does not power the board, only senses it and drives voltage levels accordingly.
Until you get a tool, look at Nick Gammon's bootloader page:
If you have room, put an ICSP header on the board and an FTDI header. If not, make a break out cable to go from the programmer cable/connector to the appropriate pins on the board.
I've posted pics of my TQFP 1284 board with MKii plugged and with FTDI plugged in also to supply power. Many ways to get there. I've even used 3 AA battery pack to power a 2560 board while bootloader was being installed using MKii.
Some people have modified their MKii adding a 3.3V regulator and a switch to bring 5V from USB connector to regulator, and a switch to bring 3.3V or 5V to the ICSP connector.
http://forum.arduino.cc/index.php?topic=114250.0
I haven't modded mine yet tho.
Nick,
Thanks for the links to such awesome, well thought out examples. Huge help! I just had a quick question. I have one of these FTDI Friends FTDI Friend + extras [v1.0] : ID 284 : $14.75 : Adafruit Industries, Unique & fun DIY electronics and kits
Does this change anything? Could I use this to just straight up program the chip without the need for the extra "programming" arduino?
EDIT:
Also I am going to be using those pins for SPI, will that interfere if they are hooked up to an LCD screen when I go to program the ATmega?
FTDI is good for serial downloading after bootloading.
I use FTDI modules connected to header pins to download into standalone boards all the time. Form factor not critical, just need to make the proper connections.
SPI pins - if your external device is not driving the SCK, MISO, MOSI pins to interfere with the programmer, you will be fine. If it can drive MISO, make sure it's chip select/slave select pin is pulled high while the uC is in reset under programmer control so MISO is not interfered with.
What he said.
You need the extra Arduino to put the bootloader there in the first place.
High five Nick! (we have a smiley face equivalent? 8) )
Wow, okay, I give you both +1,000,000! You're so super helpful but going just a little too fast for my very limited (for now!) knowledge.
SPI Pins- I'm just using it for an LCD screen, so I don't think it "drives" anything.
Now let me see if I understand everything correctly.
You suggested I go with a Atmel AVR ISP MKii to install a bootloader, this is a pretty serious project so I have no issue dropping $34 on a programmer. Does this work through the Arduino IDE "burn bootloader" tool, or do I need to learn a whole knew method?
CrossRoads:
If you have room, put an ICSP header on the board and an FTDI header. If not, make a break out cable to go from the programmer cable/connector to the appropriate pins on the board.
Note: I'm planning on putting in an FTDI header, so I can power the chip through that when I need to. With that in mind, does the Atmel AVR ISP MKii hook right up into the ICSP for programming? How exactly does it work?
Thanks again! Very helpful and I am very grateful!
You suggested I go with a Atmel AVR ISP MKii to install a bootloader, this is a pretty serious project so I have no issue dropping $34 on a programmer. Does this work through the Arduino IDE "burn bootloader" tool, or do I need to learn a whole knew method?
Yes, that's one way. Or if you have a spare Uno you can use that.
Note: I'm planning on putting in an FTDI header, so I can power the chip through that when I need to. With that in mind, does the Atmel AVR ISP MKii hook right up into the ICSP for programming? How exactly does it work?
Read this, maybe: Gammon Forum : Electronics : Microprocessors : How to make an Arduino-compatible minimal board
Nick, I went ahead and read it. So I can use my current Arduino Pro Mini 3.3v @8MHz to program the bootloader using the pins on the ICSP but not necessarily using the programmer. This will work perfect, I think I have everything I need to get my board up and running. One quick question, I noticed on the Mega datasheet (give by arduino) that the reset pin is not pulled high by a 10k resistor, but in all of you're breadboard examples it is. Should it be tied high? I know grounding it resets the micro-controller so do you just pull it high so it's not a floating value on the pin?
It has an internal pull-up but people tend to put the resistor to make it a stronger pull-up.
Atmel recommends pulling it high.
AtmelAVR042 AVR Design Considerations.pdf (236 KB)