Driving that IC is pretty simple, expecially if you have a dedicated SPI hardware interface, like many microchip has. The ATmega8, used in this example has a dedicated SPI Control Register (SPSR) that one can use to setup the SPI interface. This library can drive more then one MCP49XX of the same series at the same time, this is done just by selecting the chip using a SS channel for each one.
This project describes a simple low-current meter I devised to check the sleep current of different microcontroller circuits, such as ones based on AVR microcontrollers. It’s capable of measuring currents of between 10µA and 30nA with reasonable accuracy, using an ATtiny84 and a few other low-cost parts
tinyPulsePPG, an ATTiny85 Pulse Oximeter with Photoplethysmogram (PPG) display by Jeff Magee:
This project implemented on an ATTiny85 displays a moving Photoplethysmogram together with pulse rate and estimates of SpO2 – blood oxygen percentage. It uses an SSD1306 128×32 OLED display and a Max30102 sensor. It is emphasised that this should not be used for medical purposes. The computation of SpO2 is very approximate and not calibrated in any way. The project is an exercise in software and hardware parsimony.
This tuner circuit is a quick prototype which I build to test the RDA5807M FM radio tuner IC. RDA5807M is a single-chip tuner IC with RDS and MPX decoder, and it equipped with I2C interface for control. This receiver builds around Atmel’s ATmega16A 8-bit MCU. The output stage of this design consists of AN7147N, 2×5.3W audio power amplifier.
Although I’ve been working with AVR MCUs for a number of years now, I had never made a high voltage programmer. I’ve seen some HVSP fuse resetter projects I liked, but I don’t have a tiny2313. I think I was also hesitant to hook up 12V to an AVR, since I had fried my first ATMega328 Pro Mini by accidentally connecting a 12V source to VCC. However, if you want to be an expert AVR hacker, you’ll have to tackle high-voltage programming. Harking back to my Piggy-Prog project, I realized I could do something similar for a fuse resetter, which would simplify the wiring and reduce the parts count.
So you are using a bare attiny85 in your next project but don’t have room for the programming header, What do you do? I came up with the idea of using pogo pins layed out on A PCB so that they will sit on top of the Attiny85 legs. I used standard male jumps at each end of the chip to help line it up.