ATTINY85 Programmer Using Nano

This is a programmer for an ATTINY85 using a Nano as an ISP. There are any number of Internet articles on how to build these.  My contribution just provides one way to accomplish mounting and connecting everything.

This device provides a way to upload a sketch into a DIP8 ATTINY85 using a USB connection from a PC or laptop running the Arduino IDE.  The Nano provides the necessary interface between the IDE and the ATTINY85.

As always, friend and former co-worker WTS provided copious amounts of advice, help and hand-holding along the way.  He understands this kind of thing far better than I do and many of my designs wouldn't be published without some assistance from him.

Before using the programmer the ArduinoISP sketch must be uploaded to the Nano in the normal fashion, programming it to function as an ISP for the ATTINY85.  The ArduinoISP sketch is located in the Arduino IDE under File>Examples>Built-in examples (#11 in that list in IDE version 2.2.1)

CAUTION: When using the programmer to upload your sketch to an ATTINY85 in the socket, using the normal Upload button (Right-pointing arrow) on the IDE button bar will return an error with a message to the effect that a programmer is required; the sketch will not be loaded.  It is necessary to upload sketches to the ATTINY85 using the menu pad Sketch>Upload Using Programmer.

The circuit board is seven rows sawed from a larger board.  See the link in Bill of Materials below for the specific board I used.  Any board with two parallel rows five-pin buses and a space between that will fit an IC socket will work.

Note that one row of the PCB is blank, i.e. with no connections.  I included that extra row to provide a little more physical space for the resistor and capacitors and to ease making the connections.  I didn't shrink wrap or otherwise insulate anything so care is needed to avoid shorts.  Once the device is assembled, the chances of that are low but care is needed during the wiring process.

The connections for the two capacitors and the resistor are free-form, below the board.  All else is wire wrapped but these must be soldered direct to the appropriate pins.

On the diagrams, the off-socket connection points with text labels just below them (D10-D13, GND, RST, 5V) denote the connections directly to the Nano.

The Nano mounting screw holes are 1 mm diameter and go all the way through the part.  It may be necessary to open these up a little with a 1 mm drill in a pin vise as they tend to print a little undersize.

All wiring is 30 ga. solid, using wire wrap where possible.  

Bill of Materials:

3D Printed Parts:

Body

Hold-Down (2 req'd.)

Purchased or Parts Box parts:

DIP8 IC socket

PCB with 5-pin buses (See notes above - I cut mine from

 https://www.amazon.com/gp/product/B081MSKJJX/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)

3 mm red LED

10 uF ceramic disk capacitor (label = 104)

100 nF ceramic disk capacitor (label = 102)

330 ohm, 1/8 Watt resistor (orange, orange, brown)

4 X M1.4 X 5 mm self-tapping round head screws (Nano screws)

2 X M2 X 6 mm self-tapping round head screws (PCB screws)

Male Pin Headers as follows (see diagram)

For Nano
 - 2 pcs. 3-pin headers (GND-RST-5V and D10-D11-D12)
 - 1 pc. 1-pin header (D13)

For PCB
 - 1 pc. 4-pin header (GND bus, adjacent socket pin 4)
 - 1 pc. 2 X 4-pin header (adjacent socket pins 5-8)
 - 2 pcs. 2-pin header (left edge, bottom two rows)
 - 1 pc. 1-pin header (D10, adjacent socket pin 1)

30 ga. solid wire

Solder & flux

Printing Notes:

PLA

0.15 mm layers

0.8 mm shells

12% infill

No supports