PlainDAQ - DAQ Module for Raspberry Pi Pico

In my previous attemp to generate negative voltage supply didn't work, so I ordered new ones to try them out.

I soldered it on and suprise, suprise. It worked (with problems which will be revealed soon)

PlainDAQ is drawing 58mA when just sitting ideally, which was a surprise to me.

To my surprise ripple was too huge about 150mV!

I tried to solder big capacitor at the outputs of the buck converters, but that really didn't change anything.

Look at my bodges

I need to figure out where the noise is coming from, any ideas?

As raspberry pi pico W is out, there is really no reasons for me inlude a wi-fi module.

I am considering removing the Wi-Fi Module and adding new features.

Any thoughts?

After a stupidly long delay, I finally managed to get PCBs for our new design, so I used them to assemble two boards, and I think they look great. I hope you all enjoy the new look!

Here is how it looks:

Doesn't it looks pretty?

I have updated the front-end, so that it's more cost effective. I am trying to build something that is affordable to everyone, so I made a lot effort in component selection.

What do you think about the new look?

Subscrine to PlainDAQ if you want to get updated: SUBSCRIBE

Note: Pre-launch page will be updated soon. The pictures shown in the pre-launch page are old.

GUI update
Hello once again!
Finally I've had time to work on PlainDAQ's GUI. I worked on vertical cursors and I came up with two ways to control vertical cursors and I am trying to decide which way is the best.

Please see the video and let me know which way you think is the best.

I've conducted a poll in Twitter and Reddit to decide which wireless module (Wi-Fi or BLE) to use and results are here:

Twitter:

Reddit

In total 110 people voted and majority of them want the Wi-Fi Module. 

Seems like I'm going for the wi-fi module. 

Finishing the PCB layout, I gotta be more careful to place the components, I am running out of space 

Developing a reconstruction filter for the DAC in PlainDAQ, to get nice looking sinewaves.
Compared Sallen-key(SK) and Multiple feedback(MFB) topologies.
MFB performed much better in the stop-band.

LTSPICE files:

https://github.com/AlperenAkkuncu/PlainDAQ/tree/main/Development/SPICE_simulation/Active_filter_comparison

I had to choose between sallen-key or Multiple feedback topology, so I compared them.

Here are the circuits that I compared:

Here are the results:

Multiple feedback performed much better in attenuating the stop band.

Added them to the schematic in my KiCAD project. I also added a switch to switch between filtered and non-filtered DAC output to see the difference between, it's going to be a fun little experiment.

With the help of the switch I will be able to generate square waves with faster rise-time by using the non-filtered DAC output which is a plus.

Subscribe to PlainDAQ if you want to get update! We have just released a new update.

I’ve been working on a number of different aspects of PlainDAQ lately. In particular, I’ve been cost optimizing the PCB, picking components that are easy to source, and working on an intuitive graphical user interface.

To help me decide, please join the Twitter poll Twitter Poll or e-mail me at alperen.akkuncu@kuncuteknoloji.com or comment below 

Recent Changes to the PCB

• I moved all the terminals to the same side so they are easier to use. (In the previous version, analog inputs and outputs were on opposite sides, which would have been inconvenient when using both inputs and outputs.)
• The front-end is a bit more complicated, but it's a lot cheaper and has the same performance.
• The form factor has changed as well. PlainDAQ was previously 75 x 60 mm, and it's now an 80x60 mm rectangle, so it has a slightly larger footprint.
• I added a new visual that displays the basic input and output capabilities of the board along with a cool diagram.
• I added a Qwiic connector.
• I changed the terminal to a more affordable type. The new terminals also accept Dupont cables which is going to make it easier for you to interface with PlainDAQ.

Help Me Decide Between Wi-Fi & Bluetooth…

I need change the wireless module, but I need your help to decide between…

1. An ESP-WROOM-02 Wi-Fi module (first render below)
2. An HM-BT4502(A) BLE module (second render below)

New PlainDAQ with ESP-WROOM-02 (Wi-Fi)

New PlainDAQ with HM-BT4502(A) (BLE)

To help me decide, please join the Twitter poll Twitter Poll or e-mail me at alperen.akkuncu@kuncuteknoloji.com or comment below 

I've been working on a new revision of PlainDAQ and I had an empty space left on my PCB. I decided to fill it up with some visuals related to sampling theory.

Here is what I've drawn: The thick line supposed to be the signal that's being measured and the dotted line supposed to be the reconstructed waveform. To be honest not sure if it's terrrible accurate depiction.  

Let us hope that it will be printed well on the silkscreen layer  

I drew this on inkscape and imported it to KiCAD via image converter.

I've been thinking about what features to add to PlainDAQ's GUI.

Here is one of them: Movable/Interactive Vertical cursors for viewing real-time statistical data.

Simply by using middle mouse button and dragging it while holding the middle button you can place veritcal cursors. You can analyze the data in between the cursors.

Some people said that it's very wierd to use middle mouse button for that purpose. What are your thoughts?