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 main problem for “very small devices” – until now – was the “File System”: everybody knows “FAT”, “NTFS”, … but have you ever thought of a file system on a small chip? Or even inside of a CPU? No problem, with the right Software. This is why I wrote “JesFs – Jo’s Embedded Serial File System“
This project as described in www.surfncircuits.com came about because I needed a retro looking linear meter for my espresso maker water tank. I’m always running out of water in my espresso maker, and a cool display letting me know how much water is left and to let me know when to fill it up is definitely needed. In this project, I’ll create a HAT for the Raspberry Pi that can drive two IN-9 or IN-13 linear Nixie tubes. While I’m using this HAT as a single water meter display, this same linear display would be great for showing temperature, bar graphs, audio VU meters, even surf heights by days of the week. The Nixie Tube Power Supply, designed in an earlier blog will work perfectly to drive up to four of the IN-13 Nixie tubes or one IN-9 Nixie tube.
It’s been a while since my last blog post. During this past year, I’ve built a few other cameras yet released on this blog. In the meantime, I have been looking into options to make this work available to fellow amateur astronomers as a viable product. One major blocker here is the cost. FPGAs are expensive devices due to two factors: 1. They are less produced compared to ASIC and still uses state of art silicon process. 2. Massive area dedicated to routing and configuration logic. Let’s look at a simple comparison. The MicroZed board I’m using cost $200 with dual Cortex-A9 core clocking at 666MHz. This contrasts with quad core Ras Pi 3B clocking at doubling frequency. And it only cost $30.
In the last couple of years, I tried several powered USB hubs to drive some development boards and USB peripherals. Most of the USB hubs which we can find in the local market are unreliable or not designed to drive more than 500mA of a load. After having a few bad experiences with powered USB hubs, I decided to build a USB hub by myself. I specifically design this hub to drive USB powered development boards and experimental peripherals.
In “Eclipse JTAG Debugging the ESP32 with a SEGGER J-Link” I used a SEGGER J-Link to debug an ESP32 device with JTAG. I looked at using one of the FTDI FT2232HL development boards which are supported by OpenOCD. The FT2232HL is dual high-speed USB to UART/FIFO device, and similar FTDI devices are used on many boards as UART to USB converters. With OpenOCD these devices can be turned into inexpensive JTAG debug probes. This article shows how to use a $10 FTDI board as JTAG interface to program and debug the Espressif ESP32.