Summary of ISP Clip for ATtiny44/84 (or others!)
This article describes a DIY in-circuit programming (ISP) clip for ATtiny microcontrollers. The author, frustrated with removing chips or adding headers, repurposed a 3M spring-loaded DIP clip. By gluing a 6-pin ISP header to the side and connecting wires to the clip pins, they created a reusable tool. This allows testing and debugging of ATtiny44/84 and ATtiny85/45 chips directly on a breadboard or soldered circuit without disassembly, using standard Arduino IDE programming methods.
Parts used in the DIY ISP Clip:
- 3M spring-loaded DIP clip
- 6-pin ISP header
- Wires
- ATtiny84 microcontroller
- ATtiny44 microcontroller
- ATtiny85 microcontroller
- ATtiny45 microcontroller
- Arduino IDE
- Commercial programmer or Arduino board
I got my start in microcontrollers with the Arduino, as many of us outside of electrical engineering did. (And still do!) The ease of programming that little board makes it a great gateway… and like any gateway, sometimes you go through.
Most of my projects now don’t use Arduinos directly. For simple microcontroller applications, it’s much more cost-effective to use a bare microcontroller selected for the memory size and pin-count you need to do the job. For me, that usually means either the 8-pin ATtiny45/85 or the 14-pin ATtiny44/84. Both can now be programmed directly using the Arduino IDE with either a commercial programmer or with an Arduino, as described on the excellent MIT High-Low Tech site.
One frustration with these smaller microprocessors, though, is that I either had to take them out of the circuit and wire up a breadboard as shown at MIT’s site, or build a 6-pin ISP connector into my project. I built a 6-pin ISP-to-breadboard adapter assembly, which often helped during the prototyping process, but it was not ideal. What I really wanted was something that would clip directly to the chip and let me reprogram it without removing it from the breadboard or circuit.
It turns out the solution had been sitting in my toolbox for the last 15 years, I just didn’t know it! Years ago, someone gave me a set of “DIP clips”: they’re a spring-loaded clip made by 3M that grabs a DIP chip from the top and provides easy contact points to each pin. They’re still sold here and elsewhere. I glued a 6-pin ISP header on the side of one of these with wires from the ISP header to the appropriate pins on the clip, and voila! A ISP clip.
This one is for the ATtiny84 (or 44): I just plug my ISP programmer to the clip and put the clip on the ATtiny84: I can then test and debug the microcontroller while it’s in the circuit —even if it’s soldered into the circuit— without having to build an ISP header in the circuit. There’s another 8-pin clip that does the same for me with the ATtiny85 (or 45).
For more detail: ISP Clip for ATtiny44/84 (or others!)
- How can I program bare microcontrollers cost-effectively?
Use an 8-pin ATtiny45/85 or 14-pin ATtiny44/84 selected for your memory and pin needs. - Can I program these chips using the Arduino IDE?
Yes, both chip types can be programmed directly using the Arduino IDE with a commercial programmer or an Arduino. - What was the main frustration with smaller microprocessors?
The need to remove the chip from the circuit or build a 6-pin ISP connector into the project. - Where did the idea for the solution come from?
It came from a set of 3M spring-loaded DIP clips that had been in the author's toolbox for 15 years. - How is the ISP clip constructed?
A 6-pin ISP header is glued to the side of a DIP clip with wires connecting the header to the appropriate clip pins. - Can this clip test chips already soldered into a circuit?
Yes, it allows testing and debugging even if the microcontroller is soldered into the circuit. - Does this method require building an ISP header in the circuit?
No, you do not need to build an ISP header in the circuit to use this clip. - Is there a specific clip version for the ATtiny85?
Yes, there is an 8-pin clip designed specifically for the ATtiny85 or ATtiny45.
