In my first attempt of using solder paste with a stencil on 0.5mm pin spaced TQFPs, I ended up with solder bridging UNDER THE CHIP which made removing excess solder with braid a bit of a challenge! I suspect that having pads that would work with BOTH TQFP and TQFN parts (Adafruit breakout adapter boards) was the issue here, if the pad layout is not smaller than the part footprint, you won't have that problem. (The Adafruit board pad layout was both smaller than the TQFP and larger than the TQFN footprints to work with both.) I didn't use a hot plate though, I soldered with a hot air tool, but kept the air flow low to avoid blowing the parts around. I don't seem to get the 'jitters' from coffee, in fact it may actually help me by my being more alert (at least in the morning). There are now newer AVR chips with up to 128K of flash that are more capable and lower in cost than the now ancient atMega2560 series. Unless you really need the extra flash, you might want to look at them, there is a third party arduino board support for them. (avrDAxxx and avrDBxxx series).
Yeah exposed pads under a chip sounds like it's just asking for trouble with shorting. As for upgrading to other chips down the line, I'm tempted to get into more arm stuff (atsamd in particular for the dfu capability). I have some past experience from school/work but just never got into using them for personal projects. Now's not a good time though to switch chips with the shortage going on and excessively long lead times, but once things settle down and my stash of atmega chips shrinks I'll definitely look into it.
Sorry, but I'm not sure with the component C7 who is design like a resistor but with description of capacitor 0.1uF, and devicename R0603. What's the good value. Maybe a bad interpretation from my part. Sorry for the disturbing but I'm very interresting with your project. I would like do it. Thank you.
I probably accidentally selected the wrong footprint. If it's labelled C7 it's supposed to be a 0.1uF capacitor (voltage rating 5V or above will be fine).
Hi, I designed a board based off of this one for a project but I'm having trouble burning the bootloader with USBasp. From reading online it seems people generally have problems with the fuse values. Did you run into any trouble flashing the bootloader or was it a smooth process?
I had no issues flashing the bootloader. So if you burn the bootloader with the arduino ide the fuses are automatically set in the board file for you. Can you describe how you are trying to burn the bootloader (what are your settings, etc)?
@@sjm4306 I've tested it out on another Arduino Mega and it worked without any flaws. I followed your video and selected the board, com port, processor, and for the programmer I used USBasp. I figure the problem might be in the connections on my PCB. I went over the eagle files you have on hackaday and noticed that on the ICSP pins and the pins on the bottom of the board it doesn't look like you have VCC connected to anything, whereas I have those pins connected directly to VCC on the atMega2560. Do you think this could be my issue?
I've just noticed on my design that I have two GND layers where you have a GND and a VCC layer, so it makes sense if all of your VCC pins are connected directly to that layer. I have all of my VCC pins connected via routing. I was thinking that maybe because of this, the voltage drop from the VCC source to the MCU might result in the MCU not receiving enough power, which is why it is not being detected when I try burning the bootloader.
All Vcc points on my board are connected via the flood copper pour. They don't look connected till you run ratsnest which calculates the polygon pours. Did you inspect your soldering of the 2560 under magnification? The pin pitch is pretty tight and it's possible there's an unlucky cold joint that prevents the chip from being connected properly for programming. Also what specific error does the usbasp give when it fails?
Hi, I tried to read your Eagle schematic in EasyEDA, as a basis for my own project, but it fails. Is your minimalistic schematic available somewhere, or a link to your EasyEDA project if there is one? Cheers, Hugo
Eagle schematics are openable in Eagle, a pcb cad program. EasyEDA is a completely separate cad program with it's own proprietary file format. Files for the two are not cross compatible. I uploaded a picture of the schematic to the project page: hackaday.io/project/184213-minimega-diy-arduino-mega-atmega2560-dev-board
Have you ever added an analog stick to a gba or Ds before? That would be cool to see how. I loved your gb micro video I used it to put mine back together yesterday and your GBP video on biverting
You did really well there! But if I were going down that path I'd have gone for a pic32, which is a five-stage pipeline mips r4k basically, and all you'd need is a jtag adapter (that can be easily done with a leonardo) to program and debug it. You can also use jtag with the 2560.
Thanks, yeah I'm up to try the pic32. I'll have to look into using a leonardo as a jtag adapter, thanks for the tip. This is just an intermediate step, I really wanna get into arm processors in the long run.
Well, I said leonardo because that's what I used in the begining, but any 3v3 board would work. You don't even need to implement jtag as I did, there are firmwares out there for pretty much any programmable board. arm, I normally use bluepills, and have used arm7/9/11, but I personally prefer mips any day, even if I have never been a fan of microchip, or if these pic32 are still buggy.
I first started on low/mid range pics when I was a teen (ah the pic16f84a written in assembly using notepad, a command prompt compiler, and a diy parallel port programmer) but outgrew them and got sick of some of the limitations so I moved onto atmegas for personal projects. In college I had some arm experience but mostly dsp stuff and a sprinkle of fpga/cpld. Now I'm getting to the point that I want more power/ram/flash/io/peripherals and while I'm comfortable with atmega I want to try something new.
Well, more or less same for me, with the difference that I got seriuos with jtag. Ever since, I mostly use arduinos as usb to jtag adapters, and whether it's a jtag-capable atmega, a mips, a stm32, or a power PC or ARM (from photopiers/MFC printers' boards), I always bring out a female rs232 with proper terminations in all my projects, so that I can access the core at any time.
