4 ms·
I’m pretty sure that Raspberry pi’s draw more than that. But if you have a good way to fix this I’d like to know. The pi supply hat also has that probably and
by hcfman 2y ago
I’m pretty sure that Raspberry pi’s draw more than that. But if you have a good way to fix this I’d like to know.
The pi supply hat also has that probably and no one has fixed it in a couple of years.
- 15155 2y agoYeah: don't use a Raspberry Pi or any similar Linux SOC to translate sensor data to TCP/IP. GP said "cheap MCU" - which I agree with. Ambiq MCUs use 1mA while active, but most ARM M0+ cores (RP2040, STM32) are going to be sub-50mA generally. Spin a $2 4L PCB with all the POE circuitry (and receptacle), MEMS microphone IC, and MCU onboard. This whole thing should cost <$25 total.
- hcfman 2y agoWell.. the project wasn’t intended to be an acoustic recording device for biologists. It was intended to be a microphone addition to a security project I have that would dynamically merge audio with video. Something you can’t do with microcontrollers. But along the way, I added a GPS to keep the time accurate and then with the sub-microsecond time accuracy I thought of sound localization. So I developed it further into a sound localizing recorder with in principle enough time accuracy to localize bats that are close even. With the power of a pi and sub-microsecond clock timing, coupled with a linkage into jackd that can support multiple consumers, you can both record and still have enough CPU to on principle perform real time bird recognition and localization. That is not going to be possible on a microcontroller. With this project I have been able to localize explosions to less than 20m accuracy from microphones located more than 3km away. Again not something possible on microcontrollers. The setup of the author is at his own home. Which means that in principle he’s not constrained by power. With that’s setup by adding icecast2 and darkice. Whilst still recording and not needing a big host host computer. Likely even better with go2rtc. Next on my list to try.
- 15155 2y agoWhy do you need to merge these items at the point of collection? Why not just stream the sensor data off with temporal correlation data and assemble them elsewhere? Either way, galvanically isolating 5W isn't too terribly hard either.
- hcfman 2y agoBecause you can. Why split the architecture across multiple machines when it works on one. Do you have any recommended links to that galvanic isolation I could look at ? I’m encouraged by your view on this.
- 15155 2y agoI don't really want more Linux boxes floating around if I can help it. https://www.analog.com/en/products/adum6000.html https://www.analog.com/en/products/adum6000.html Things like this are a fancy way to go about it - otherwise very-filtered flyback will probably get you where you need to be.
- hcfman 2y agoI've tested this device and that works. Nice clean power on the microphones whilst running over POE. https://thepihut.com/products/power-filter-board-for-raspberry-pi https://thepihut.com/products/power-filter-board-for-raspber... The chip you point to suggests a much simpler approach. Is it really that simple? There are a great many more bits on the board I point to. Why would they take a hard way if one simple chip can do it ?
- 15155 2y agoThe board you linked isn't a galvanic isolator, it's just a capacitor bank covering a bunch of different frequency ranges. The ADUM isolator I linked as well as flyback converters use transformers to provide a high-voltage isolation barrier between the source and device being supplied. Transformers are generally larger, more expensive, and less efficient than non-isolated DC circuits. The POE supply itself is isolated (with a transformer) and doesn't need to be noisy necessarily - but if you want even more quiet, another level of isolation can't hurt.
- jononor 2y agoOlimex ESP32 POE ISO with a PDM or I2S microphone breakout board is an easy version without having to create a custom board.