hello everyone !
I have a question where you may have the awnser to.
I’m making my own Arduino uno rev 3 right now, and was wondering wich housing i need for the 2 Atmel’s on the board ?
I have included a screenshot so you can see what type of atmega components they are.
I know KiCad has those symbols and footprints of them but the pinout is a bit different. ( I’m probably going to make those symbols myself ).
ATMEGA16U-MUR is a VQFN-32 with exposed pad (At least according to digikey)
The packaging details are in the datasheet page 297.
The closest fitting one in the official lib would be
QFN-32-1EP_5x5mm_P0.5mm_EP3.8x3.8mm (Name as found in the v5 lib. This fp is not present in the v4 lib. The closest one in the v4 lib has an exposed pad of 3.45x3.45mm)
The one i give above has a slightly too large exposed pad. (I would guess better would be something between 3.6x3.6 to 3.75x3.75mm depending on your manufacturing tolerances and clearance needs.)
ATMEGA328P-PU would be a DIP 28 (Again digikey)
Part drawing is in the datasheet page 439
If there is a fitting part it is in Package_DIP (Housings_DIP in kicad 4)
DIP-28_W7.62mm should fit. (named the same in the v4 and v5 lib)
For details about how to arrive at footprint dimensions from datasheet drawings see: Tutorial: How to make a footprint in KiCad 5.1.x (From scratch)?
Wow thanks. I can do a lot with that info @Rene_Poschl !
The ATMEGA16U-MUR should be a 32 QFN 5x5mm 0.5mm pitch,
Package_DFN_QFN:QFN-32-1EP_5x5mm_P0.5mm_EP3.6x3.6mm in V5RC looks good
The atmega im using is going in a holder for it. Does that change the footprint ?
Yes the footprints we mentioned are for the part it self. For the footprint of the socket you need to look at the datasheet of the socket. (Do your self a favor and make the two footprints in the faq tutorial i linked above. You should get a clear understanding of what needs to be done to get from datasheet to footprint depending on what the datasheet gives you.)
Do you mean the DIP, the QFN or both. It is common for the DIP to be socketed so the the board can be used as a programmer
Make sure you use the data sheet (or the figure in an all encompassing data sheet) for the specific chip package you want to use on the schematic as well. It is common on ICs (particularly large pin count ones) for the different packages to have different number of pins. For example on the 328 used for Arduino, the DIP variant doesn’t have the pins used in Arduino for A6 and A7 so the UNO doesn’t support those pins, but the QFP version on the Pro Mini has those pins so SparkFun elected to include those pins. Also, the pin numbers for the same functions may be different due to how the silicon die lines up with the lead-form that makes the legs that exit the body of the completed IC package.
If you’re going to “re invent” an arduino board, then consider to put in a small SMPS instead of a lineair regulator.
This will allow a much wider input voltage range without heating problems, and will also make your uC board more robust because the inductor stops a lot of conducted EMI / noise comming from the power supply wires.
you may or may not find what you look for here
yeah the DIP gets socketed.
And thanks all for the replies !
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