Products > Crowd Funded Projects

PlainDAQ - open source DAQ module for Raspberry Pi Pico

(1/11) > >>

palpurul:
Hello,

I've pre-launched another project on crowdsupply. It's a simple open-source DAQ module for the Raspberry Pico.

Subscibe to PlainDAQ, if you want to get notified when we go live: https://www.crowdsupply.com/kuncu-teknoloji/plaindaq

It's a simple board with 4 analog inputs and a single analog output, hence the PlainDAQ  :D, I still doubt if it's a good name for a product.  :-\. It can also output +/- supply voltage for powering circuits that need symmetrical power supply. Optionally it comes with ESP-WROOM-02 (wi-fi) module.


Here are the updated pictures! 👇👇👇






Brief:


Components:


Now Let's talk about the precision stuff  :D :D
Note: I will update this section as I verify any specifications that is specified right now.

The PCB is on its way, right now it's stuck in the customs for some reason  :-//

Analog Inputs:

* 12-bit resolution

* Max. 500 ksps samling rate
* SNR, ENOB, noise: To be determined
* Differential Input ADC (Increase noise immunity)[/i]
* 4 high-impedance buffered channels (low bias current)
* 4 bipolar ranges. ±0.5 V, ±1 V, ±2 V, ±4 V
* Auto-offset calibration
* Bandwidth: To be determined
Voltage Reference:

* 2.5 V, 20 ppm/°C (Typical) Drift
* Calibrate to 0.05 %, Stored in as ROM as calibration data
Analog Output:

* Single channel
* Buffered low-impedance output
* 10-bit resolution
* SNR, ENOB, noise: To be determined
* Max. 50 ksps samling rate
* Bandwidth: To be determined
Bipolar Voltage Supply:

* +/-5V supply voltage
* +/-100mA current rating
I am trying to make it as cheap as possible while trying to provide a semi-precision DAQ unit that can be used with Raspberry Pi Pico, so I need to make some compromises between cost and accuracy, it's not very easy  ;D

PlainDAQ will communicate through USB to graph captured waveforms, I will prepare a simple GUI for that purpose. There are lots of things to make in the software side of things (both GUI and embedded). I’d like to list the thing that are not implemented, but will implemented in the future, I share progress log I there is a progress 😊

Things to implement/test:

* USB speed test, gotta reach to at least 6Mbit/s (USB full speed runs 12Mhz ☹) Edit: 22.02.2022 7Mbit/s transder speed is achieved
* Rising/Falling edge trigger
* Graphing software
* Simple Python scripting for controlling PlainDAQ
* Measuring analog inputs’ SNR
* Measuring analog output’s SNR
* Measuring analog inputs’ bandwidth
* Measuring analog output’s bandwidth
* Measure the effect of ESP32's operation on SNR (Added on 14.02.2022, kudos to @Kean)I will add to the list when I need to add a new feature based on feedback.

Tell me what you think. This is the first Crowdsupply project that I am running, wish me luck 😊.

PlainDAQ also comes with its GUI, here is a sneak-peek of the GUI:

mikerj:
Is there any kind of protection on the ADC and DAC pins to prevent damage from ESD and overvoltage?  This seems to be a common failing with basic DAQ designs, but is pretty essential for any real world use.

palpurul:

--- Quote from: mikerj on February 14, 2022, 09:21:51 am ---Is there any kind of protection on the ADC and DAC pins to prevent damage from ESD and overvoltage?  This seems to be a common failing with basic DAQ designs, but is pretty essential for any real world use.

--- End quote ---

This is the first prototype, honestly at this stage I was rushing to have my hands on something working, so omitted input protection on the board shown in the pictures.

I will keep your suggestion in mind and next revision will include input protections.

Thank you for your suggestion. These kind of feedbacks really help.  :-+

Kean:
This looks interesting.  Will you be publishing the schematic?  That will help some users like me to understand suitability for an application.

I'd be interested in whether you see any increased noise (lower ENOB) when used with the optional ESP32 & WiFi, assuming the ESP32 is meant to mount on the back of the PCB.  Especially with the 14-bit ADC option.

Just a suggestion - You may want to spend a little extra time on assembly for the next sample PCB.  The soldering is a bit rough on the above pictures, and some of the terminal pins aren't even soldered.

palpurul:

--- Quote from: Kean on February 14, 2022, 12:38:47 pm ---This looks interesting.  Will you be publishing the schematic?  That will help some users like me to understand suitability for an application.

--- End quote ---
It's all open-source. I will release the whole KiCAD project. I will also release all of the firmware that I wrote for it.


--- Quote from: Kean on February 14, 2022, 12:38:47 pm ---I'd be interested in whether you see any increased noise (lower ENOB) when used with the optional ESP32 & WiFi, assuming the ESP32 is meant to mount on the back of the PCB.  Especially with the 14-bit ADC option.

--- End quote ---
That's an interesting point. I've never thought about it actually, it would probably increase the noise. Obviously this increase is going to be more pronounced at higher resolution as you pointed out. ESP32 module is something that I added just before the pre-launch page is released, actually the boards that you see in my post does not include the ESP32 module yet, It's for another update. The board is a 4-layer board and the ESP32 module will be on the bottom side, so maybe ground plane would help to combat this issue.
Anyways, it's going to be fun to test it and I will definitely post the results here  ;D (added to Things to implement/test list)


--- Quote from: Kean on February 14, 2022, 12:38:47 pm ---Just a suggestion - You may want to spend a little extra time on assembly for the next sample PCB.  The soldering is a bit rough on the above pictures, and some of the terminal pins aren't even soldered.

--- End quote ---
I know a person with a keen eye would someday notice the flaws in my hand assembly, you are first, so congrats  :D
I didn't solder all of the pins because I had a single sample at the time I was taking the pictures and I needed it take its pictures of it with and without the raspberry pi pico on top, and therefore I left most of the pins unsoldered.
Excuses excuses I know.  :-//

Consider subscribing to mailing. I will post any updates here, but if you want to get notified you can sub here :-+

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version