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
The overall architecture is very simple; There is a python script that is running on a PC and collects CPU, memory, network and GPU usage. Then, it sends that information over serial COM port to the hardware monitor board for processing. New voltage values are calculated and passed to the digital-to-analog converter (DAC) which drives analog dials (galvanometers) by applying a voltage that will move the needle to a desired location. Super simple but it get’s the job done.
The only way to make CAPS LOCK even more annoying was to make it audible! Now never type a password in all upper case, join 500 lines together in vi, or turn a harmless forum post into an ANGRY SCREED without warning again! This project uses a PIC16F1459 to monitor the USB output report containing the CAPS LOCK status from the connected PC. When CAPS LOCK is enabled, the PIC turns on an annoying warning buzzer.
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.
The meter is powered by the micro-USB port on the ESP-12E. I soldered header pins onto the IN and OUT terminals of the LTC-4150. The whole idea is that one could plug the source battery into the IN terminals, and plug the circuit to be tested into the OUT terminals, press the “Reset” (RST) button on the ESP-12E, and it will start measuring the average current draw of the circuit.
In JTAG Debugging the ESP32 with FT2232 and OpenOCD I have used a FTDI FT2232 breakout board to JTAG debug with OpenOCD. With an adapter board on top of the FTDI FT2232 the wiring is much easier and simpler to use.
This is a USB-stick sized UPDI programmer, for programming Microchip’s new 0-series and 1-series ATtiny chips from the Arduino IDE It’s based on an ATmega328P, and is essentially an Arduino Uno on a USB stick, so you also could use it as a mini-sized Arduino Uno.
Nigan tipped us to a simple open source Bluetooth stack for embedded devices, the SmallTooth:
A newly developed open source Bluetooth stack for PIC32/24 * The code is really easy to understand, very well documented and really small. * Designed to be extended and ported. * Works straight out of the box with the PIC32 USB Starter Kit II and should be fairly simple to port to other PIC32 or PIC24 boards.
Our LED light-sensing experiments lead to an interesting observation: When these loggers are left running overnight they still produce readings because reverse-bias ‘leakage-current’ eventually triggers the Interrupt Capture Unit (ICU) – in the absence of any light. The speed of this self-discharge depends on the ambient temperature. If you deliberately cover an rgb LED with heat shrink, the different color channels have different rates of thermal decay
The primary reason we ordered these now is to get a feel for how the pinout color scheme works in practice before we commit to it permanently.
The leads are 30cm long, which seems a bit unwieldy in real life. The next version will be a few centimeters shorter.
One end is terminated with 1 pin female “DuPont” connectors. These are easy to use with breakout boards and bread boards that have 2.54mm header pins. We’ll need to choose a nice probe hook and mating crimp eventually.
While the wire quality is fine (top), it’s a bit stiff and we’d prefer something really nice for the final cable. The Saleae Logic cable (bottom) has really amazing tangle free wire with great flexibility. We took the Saleae cable to a bunch of wire manufacturers in Shenzhen, but none of them had anything close in terms of quality and flexibility. Our search will continue.