Adjustable USB Power and Measurement Board
Posted: Wed May 25, 2022 3:10 pm
As you can see from this Forum, I have been working on a number of ESP32 based projects. It would be really handy to be able to have a USB based power limiting function and at the same time, be able to measure power being used at high speed, say at least 20K Samples Per Second (SPS). This would help quantify low power usage on some of my projects.
In this project I have drawn ideas from this nice board: https://www.nordicsemi.com/Products/Dev ... ofiler-Kit
This first version of my board is an Alpha version to test out some of the circuitry that I might use going forward and to test out some of the software. Some of this is very similar to my USB Cable Tester Board, so it didn't take too long to put together some circuitry: It's all laid out into a number of switched blocks. By switched, I mean under ESP32 control, I will be able to switch various paths and blocks on and off. I have included a set of three current calibration test loads: 1A, 500mA, 100mA
It includes an adjustable 1.8V to 5V Regulator based on an adjustable MCP1827 LDO and a 100mA to 1.1A current limiting switch based on the MIC2097. Both of these are adjustable via i2C based variable digital resistors. This will be a first for me, so it will be interesting to see how these work out.
The above adjustments can be bypassed via MOSFETs and I use either RU30L30 or WST2011 (dual MOSFETs back to back) high side MOSFET switching around the board. Each block has a WS2812 RGB LED to signify it's status. It looks quiet colourful when they are all lit up: Funny story: So, some time back, I discovered that LCSC stock 2mm x 2mm WS2812 based RGB LEDs. These are a wonderful size to use when you have a pretty full PCB and not much spare space left for a bit of photon bling. I quickly used them in my next three projects with out closely examining the pinouts, I mean it kind of looks ok? Fast forward to the first PCB arriving and my dismay when the RGB LEDs would not light up! Yep, for some reason the manufacture has rotated the footprint by 90 degrees. You can still use them, but the footprints are a bit out and so you need to hold the LEDs in place while hot airing them down, otherwise the surface tension pulls them askew. Oh, and if you do power up a board with them out of place, it fries them out.
As you can see in the photo above, the adjustable voltage regulator is not the size I expected and I had space to mount it dead-bug style by scratching away some of the solder mask and hot airing it into place.
I have already learnt about some SPI based ADC IC's like the ADC124, so the next version will incorporate one of these, so that will give me a much faster current and voltage measurement in the next version of PCB. This journey has just begun!
In this project I have drawn ideas from this nice board: https://www.nordicsemi.com/Products/Dev ... ofiler-Kit
This first version of my board is an Alpha version to test out some of the circuitry that I might use going forward and to test out some of the software. Some of this is very similar to my USB Cable Tester Board, so it didn't take too long to put together some circuitry: It's all laid out into a number of switched blocks. By switched, I mean under ESP32 control, I will be able to switch various paths and blocks on and off. I have included a set of three current calibration test loads: 1A, 500mA, 100mA
It includes an adjustable 1.8V to 5V Regulator based on an adjustable MCP1827 LDO and a 100mA to 1.1A current limiting switch based on the MIC2097. Both of these are adjustable via i2C based variable digital resistors. This will be a first for me, so it will be interesting to see how these work out.
The above adjustments can be bypassed via MOSFETs and I use either RU30L30 or WST2011 (dual MOSFETs back to back) high side MOSFET switching around the board. Each block has a WS2812 RGB LED to signify it's status. It looks quiet colourful when they are all lit up: Funny story: So, some time back, I discovered that LCSC stock 2mm x 2mm WS2812 based RGB LEDs. These are a wonderful size to use when you have a pretty full PCB and not much spare space left for a bit of photon bling. I quickly used them in my next three projects with out closely examining the pinouts, I mean it kind of looks ok? Fast forward to the first PCB arriving and my dismay when the RGB LEDs would not light up! Yep, for some reason the manufacture has rotated the footprint by 90 degrees. You can still use them, but the footprints are a bit out and so you need to hold the LEDs in place while hot airing them down, otherwise the surface tension pulls them askew. Oh, and if you do power up a board with them out of place, it fries them out.
As you can see in the photo above, the adjustable voltage regulator is not the size I expected and I had space to mount it dead-bug style by scratching away some of the solder mask and hot airing it into place.
I have already learnt about some SPI based ADC IC's like the ADC124, so the next version will incorporate one of these, so that will give me a much faster current and voltage measurement in the next version of PCB. This journey has just begun!