Thursday, April 1, 2021

1/4 Sized Breadboard


In the photo above there is Adafruit small breadboard. I found it to be a perfect match for projects utilizing Attiny85 microcontroller. 

While it is single side board, top side has copper circles around holes so components can be soldered on any side of the board. Board is not very thin and feels sturdy. Occasional soldering overheating will not damage conductor strips. Conveniently it has four strips for power and it is well suited for projects needed two voltage levels (like 5V and 12V).

So far I used such a board for two projects  made for last year Halloween  (published here). 

First project is to control two three colors LEDs. It is minimalistic: apart of controller board accommodates just three resistors. To make controller programmable in-board there is  6 pins ISP male header. I soldered pins, cut strips between two pin rows with the knife (cut is on the bottom side of the board) and wired them to corresponding pins of the the microchip.

Second project required two voltage levels (12V and 5V).  See 12V-5V stepdown power supply on the right side of the board soldered to it. There is no 6-pins ISP header on the board, Does that mean there is no way for in-board programming? Absolutely not. To make microchip in-board programable I mounted on each side of the chip female headers. Because of that board becomes suitable for AVR ISP to Attiny85 adapter  and  can  be   programmed the same as projects mounted on non-soldering breadboard.

Saturday, March 6, 2021

Capabilities of Supercapacitor


Several years ago I built the project utilizing supercapacitor (useless machine). Now I returned to this component again to make a set of small projects, which  will use super capacitor as backup power supply. Clip above shows initial test. Several seconds of charge is enough to power Attiny85 chip controlling blinking be-color LED for five minutes. At the end of this time LED blinks are barely visible but anyway I found result impressive. In case you need details, here is circuit diagram:

 And here is list of components:

  • Supercapacitor 0.1 F, 5.5 V (NEC)
  • Attiny85 microchip
  • Red-Green bi-color LED (5mm)
  • Resistor 180 Ohm, 0.125 W
  • Diode Schottky ( 1N5817) (for this test it is not really needed but later I will utilize it to detect the moment  when external power is down).
Circuit initially powered up by 5V USB 0.5 A power supply.
 Code is short, so I put it here as well.

#include <avr/io.h>
#define 	F_CPU   1000000UL
#include <util/delay.h>

typedef enum {OUT_LOW, OUT_HIGH} OutputLevel;

#define pinOut(bit, outLevel) \
(DDRB |= (1 << ( DDB##bit)));\
switch(outLevel) \
	case OUT_LOW: (PORTB &= ~(1 << (DDB##bit))); break;\
	case OUT_HIGH: (PORTB |= (1 << (DDB##bit))); break;\

int main(void)
    while (1) 

Sunday, February 28, 2021

AVRISP II adapter to Attiny85


For my hobby projects  I often use Attiny85 chip . Usually first stage of the project is breadboard prototyping. But there is the problem: connecting AVRISP programmer to the chip on the breadboard is not that easy. So I made dedicated  adapter  which allows effortless connection between  AVRISP programmer and Attinny85 chip. 


Adapter is passive: it contains nothing but headers to connect programmer and headers to connect to the chip. Apart of that added LED with resistor to indicate if power is supplied.

Adapter has two set of headers:

  •  one set to connect AVRISP (on the photo on the left)
  • another set to insert into breadboard on top of Attiny85 chip.
LED with resistor added for convince to be sure that power provided to the circuit. Marking on the circuit diagram below corresponds to the photo above.
Here you can see the breadboard with the microchip attached to the power.

I need just put adapter with connected AVRISP II programmer on top of microchip, connect AVRISP programmer to a computer through USB in interface, and start Atmel Studio.  Now I am ready to program.

One may ask why not to buy some breadboard ready ISP header? Indeed for less than one dollar you can get adapter kit at  Adafruit site. It is nicely made and can be used with any AVR device. But to make it work there is need to connect that adapter to a controller with six jumper wires. With my adapter I just need to snap it in place. Obviously, if I want to work with different controller (like  Atmega328), I have to make another dedicated adapter. Still I assume that benefits worth the effort.

Saturday, February 13, 2021

Chessboard Chair

We have a small folded chair with top made out of sawdust wood covered with  plastic . We left it in backyard for some time and it got under the rain. As a result top edges started  to decay with  plastic  partially detached. But surprisingly painted metal frame was intact. I decided to renovate the chair by changing the top. While looking for proper board I have found in our home wooden chess board which did not get much use lately. So unscrewed old top and mounted chessboard instead.  Old chair legs tips (couple of them lost) I replaced with  3/4" chair tips I bought in the local Home Depot. On the photo above you can see the result.

And here is old top. I still keep it. Maybe I can restore it and it will find another usage.