VProbe - a wireless oscilloscope probe - Page 1
Forum section: electronics / projects

author: victor_passe
author_rank: Newbie
timestamp: July 02, 2022, 10:42:25 am
content: Hi, I am a new user but long time electronics developer, both by profession and by hobby.My latest project is a wireless oscilloscope probe, I have been wondering why nobody has built such an device before as, at least for me, it seems like a verry useful product as my desk is often cluttered with cables and often measure on 230V devices with different grounds as well as on moving robots or similar.So I designed VProbe, a wireless oscilloscope probe. At its core it is a NRF52805 using the internal ADC@200ksps and the internal radio@2Mbit.The receiver uses the same CPU and a R2R DAC where the lsb is a connected to a pwm to further increase the resolution without needing high precision resistors.Here are some links to a demo video and some simple starting point for a datasheet and a technical description:https://docs.google.com/document/d/1cdKEO9LvXWRO7VYsg2WQwgSty7Dx3twJ2ib7UQk9axchttps://docs.google.com/document/d/1Fbvq9skYhKqmVh8e7Xj1D0pos_nm8Wk4GfTOS5zm7n0Future features to be added:Currently the probe can operate @ 8bit, 200ksps = 1600kbit/s or 12bit samples (16bit with ecc) @ 100ksps = 1600kbit/s or 1bit @ 1600ksps = 1600kbit/s, I am going to try to increase the useful throughput by increasing the package length (this will not increase latency) to 1800kbit/s to enable 9bit @200ksps, increase the sample rate @ 12bit and increase the digital to 1800kspsI will add a BLE mode and write a website that uses web BLE to act as an oscilloscope and can connect to several VProbes and display traces. The main problem to solve to do this is the synchronization of multiple probes but I have an idea that I think will work. One probe would be the main probe and send short sync packages at some frequency and every other VProbe will listen for the sync package and include the timing of the samples relative to the sync package to the website. The main drawback with BLE mode is that the data throughput/samplerate will be much lower. Probably around 3-5x slower then with the receiver.My goal regarding open source is to open the project and currently all source material is on my private github that I will open up when I am a bit further in the project.I am currently seeking some advice on the following points:1. Do you think the product would be useful for yourself?2. What price would you consider fair for one probe and one receiver? The current BOM price @ volume for all parts is at ~15usd. That includes ground lead, hook, spring, case(3dprint), pcb, receiver, components and so on but no assembly cost or box build cost. I could imagine the total cost including assembly to be around 30usd.3. I dont want to manage or put any time in to the production and selling of this project, nor do I intend to make any money on it, do you have any recommendation of some party that does PCBA, box build, sales and distribution?4. Do you have any feature recommendation that I should add?Any other questions?

author: BravoV
author_rank: Super Contributor
timestamp: July 02, 2022, 12:46:13 pm
content: Quote from: victor_passe on July 02, 2022, 10:42:25 amNeat, and for me, it will be useful if this wireless probe is designed more towards high voltage measurements, for example mains related measurements, no need for super duper bandwidth or samples.I strongly believed "IF" its quite safe and suitable for mains rated and relatively fair priced, people will be eagerly to own it, as owning an isolated scope is not cheap.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 02, 2022, 02:50:08 pm
content: Just put an ESP32 in the probe and use a smartphone as the display.

author: kripton2035
author_rank: Super Contributor
timestamp: July 02, 2022, 03:01:13 pm
content: already exists for sale...https://www.pokitinnovations.com/pokit-meter/https://www.pokitinnovations.com/pokit-pro/

author: victor_passe
author_rank: Newbie
timestamp: July 02, 2022, 03:06:32 pm
content: Esp32 will not be a good choice of mcu as the current consumption is too high if using wifi to give any useful battery lifetime and when using BLE, the BLE link is the limiting factor, not CPU speed or adc sample rate. NRF52805 is lower current consumption and not limited by adc sample rate nor CPU load so I dont see how a different mcu would make the project better.My plan in the future is to create a website so you can use your phone / pc as the osciliscope but I think there are several benefits with using your regular scope as the receiver. Partly performance as the sample rate will be higher without the BLE overhead and as you can mix wired probes and wireless probes. Also I find the oscilloscope interface with dials much better then the phone or PC.The main benefit with using phone/PC would be logging/screenshot ability/simplicity as well as being more portable.

author: victor_passe
author_rank: Newbie
timestamp: July 02, 2022, 03:16:10 pm
content: The pokit does not seems to be the same product, the main idea with VProbe is that it is a wireless oscilloscope probe, that allows multiple probes be be used at the same time. I have never seen a single channel bench oscilloscope so I believe the need for multiple channels is a requirement for most type of jobs. It does not seem like you can use 4 pokits to for example measure a SPI bus or similar. And is seems that it does not come with a BNC receiver so you must use the phone/PC as receiver. I have access to PC scopes as well as real scopes and I have never felt that a PC based scope is better then a real oscilloscope.Also VProbe would be around 5x cheaper which I believe would matter as buying several to use for multiple channels would quickly be expencive.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: July 03, 2022, 08:00:37 pm
content: Victor_Passe,Great idea, as for me same as BravoV posted.Jeff