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I am designing a circuit with an Attiny85 microcontroller and a temperature sensor, eventually I want everything including the battery to weigh less than 5g (preferably<3g). I want to be able to reprogram the Attiny while it is soldered to the board, so I need some way to connect the programmer to the attiny85.

I am drawing the PCB using Fritzing (pcb design program), eventually I hope it will only be 1cm by 1cm using surface mount components, though might be twice that if I put the battery on the board. I know I could just add some rows of pins next to the attiny and use the pins to connect to the programmer, but putting more pins on the board would add weight and also stop it being a nice flat design. I know I could solder and desolder the pins whenever I want to program but I think there must be a better way.

I was thinking maybe there is some way to draw tracks to the side of the board and then get some type of clip on connector which connects to the tracks?

Could anyone suggest something, that doesn't add extra weight to the board, or very very lightweight (e.g. maybe 0.2g).

Thanks in advance. Sorry if I'm missing something obvious!

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    \$\begingroup\$ Tag-connect.com \$\endgroup\$ – DoxyLover Dec 26 '17 at 7:37
  • \$\begingroup\$ @DoxyLover, thanks, that looks useful also. Since I'm probably not going to mass produce it right now I will use the USB one, or the test clip (just found out they existed). For anyone else looking at this question, there are also test clips e.g. sparkfun.com/products/13153 \$\endgroup\$ – S.H. Dec 26 '17 at 8:49
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    \$\begingroup\$ Do yourself a favor and learn to use ANY other program for your circuits and layouts. Fritzing has so many restrictions that you are severely limiting yourself. Kicad, Eagle, Target, Altium, and others are available. Pretty much any thing is better than Fritzing. If you need free, then look at Kicad. \$\endgroup\$ – JRE Dec 26 '17 at 16:33
  • \$\begingroup\$ This (pogo pins) with a 1.27mm pitch 2x3 header footprint (just holes, no need to solder anything on). \$\endgroup\$ – Tom Carpenter Dec 26 '17 at 17:46
  • \$\begingroup\$ @JRE ok, haha thanks! I will keep that in mind, at the moment just making something very simple but if I make more things in the future I probably will. \$\endgroup\$ – S.H. Dec 27 '17 at 8:38
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This technique is often used on USB pen drives, etc., where a proper USB type A plug is not fitted but the edge contacts on the PCB connect with the host - provided the device is plugged in the right way up.

enter image description here

Figure 1. Gold-plated contacts on a PCB.

If this is not for a commercial product then something like this could work well for you and you can use the female end of a USB extender cable as your programming lead and socket.

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  • \$\begingroup\$ Yes, it's not for a commercial product. Thanks I will look into this now..... \$\endgroup\$ – S.H. Dec 26 '17 at 7:49

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