Author Topic: EEZ Bench Box 3 (BB3)  (Read 58686 times)

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Offline goleszek

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Re: EEZ Bench Box 3 (BB3)
« Reply #325 on: September 30, 2020, 11:50:58 am »
Promissed summary of my implementation of the the 4-quadrant supply:

It can provide current +/-2A and voltage +/-20V to the load connected between J5 and J6. The regulation topology operates around GND, so only +/5V supply is required.

Ports meaning from the schematic:
SDAC - analog input for V or I control, +/-2V range
GENOUT - analog input from a signal generator, +/-10V range
SSOURCE - digital input for source selection ("1" - from SDAC, "0" - from GENOUT)
IVSENSE - analog output, proportional to load current or voltage, +/-2V range
IVREAD - digital input for readout selection ("1" - current read, "0" - voltage read)
IVMODE - digital input for mode selection ("1" - current mode, "0" - voltage mode)
ILIM- - analog input setting sink current, 0..+2V (reflects 0 to -2A limit)
ILIM+ - analog input setting source current, 0..+2V (reflects 0 to 2A limit)

Circuit behavior:
U27 acts as an operating mode selector
U24A buffers signal from the load for further processing by ADC/MCU
U23A and U23B act as comparators, supporting independent sink/source current limits, regardless of actual mode (voltage or current). U26B inverts control signal ILIM+.
U25B acts in a current control loop, inverting signal proportional to current, taken from R189, R185
U25A acts as an error amplifier
U26A provides a control signal, preselected by U27 mux
Q3 and Q4, with shunt resistors, act as fast comparators, limiting load current to kindly +/2A during fast switching (like driving capacitive load by a square wave). Under such a condition control loop with opamps can't compensate correctly, so some protection mechanism is needed.
U28 and U29 provide control currents - they can be realized by simple LMxx source or even resistors.
Darlington pair Q5/Q6 provides load current, being controlled by mA sources.

This supply requires floating pre-regulators or fixed voltage (if thermal budget allows it), connected to OUTPUT, VPOS and VNEG pins.

The power (PGND) and logic/control (GND) grounds are shorted by R190, however effectively conducting no current. This short is for a reference only.
 
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Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #326 on: October 02, 2020, 07:21:55 am »
Hi again, and sorry for late response I was occupied with other issue. 4Q PSU module seems very simple, but if it has proven to be stable and can handle properly changes in operating mode (i.e. with min overshooting) and going through zero, it makes sense to try to adapt it for BB3. For starters, I might do an LTspice simulation that can help with further development and modifications as well.

I also see the next candidate for BB3 that I was already thinking of adding for testing automation purposes and that is the resistor decade module. Congratulations on how you packed the relays! I guess they can't be hand soldered so densely placed and that an reflow oven is needed.
Can you publish the schematic, I wonder what ratios of resistors you used and what ranges with which steps are possible.

Thanks again for sharing this with us.

Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #327 on: October 02, 2020, 11:13:07 am »
One thing that is difficult to distinguish from the pictures, and what interests me is what the master MCU (STM32F4) directly controls. He seems to be responsible for a lot of things, so I wonder what the overall performance is. Unless in case when one of the demanding modules is active the others go to sleep or get a very low priority.

Online Kleinstein

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Re: EEZ Bench Box 3 (BB3)
« Reply #328 on: October 02, 2020, 01:16:05 pm »
I don't think the modules would need a lot of active attention from the mast µC. The DDS chips and supply would essentially run on there own, one programmed. It would be mainly the ADC read back from the supplies.

With DDS the µC could however add extra functions like modulation, and this would need quite some time / attention.

How to split the control jobs between the master and and cards is a good question though.


By nature the 4 quadrant supply would have to cope with high power loss, when in the sink quadrants. So I wonder if it is worth doing full pre-regulation. One might limit it to just plain linear, possibly with 2 steps so that the sink mode would not add much extra power from the supply.
 
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Online jbb

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Re: EEZ Bench Box 3 (BB3)
« Reply #329 on: October 02, 2020, 06:22:55 pm »
Yah, the sink quadrants are a bit vicious...

Assuming +20V on terminals, sinking 2A load. That would appear to be 40W... except that the pass transistor is sinking to, say, -25V. So it’s actually 90W or so. Yikes!

Some kind of multi-range switch - and a large heatsink - definitely required. I seem to recall that Liv (?) posted a DC power supply design here a few years ago with a Class G output stage which effectively does automatic range switching.
 
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Online Kleinstein

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Re: EEZ Bench Box 3 (BB3)
« Reply #330 on: October 02, 2020, 07:38:25 pm »
There was a lab supply project with a class G output stage from Liv.  It could be extended to 4 quadrants. With 4 quadrants just using 2 steps, one from some 20-25 V and one from zero could be enough. So the maximum voltage drop converted to heat would be some 25 V. Starting from zero could start if the external supply is higher than some 2 V. More steps would not improve the worst case power loss very much.

For not so high currents there is an odd variant, using an emitter-follower with a limited collector voltage. With higher voltage the current would be just from the base current. So the transistor changes from current amplifier to diode function. Chances are this type could be build relatively simple. It just needs a relatively robust BJT that can withstand 2-3 A of base current (e.g. something like TIP3055). For something like +-20V 2A this configurations looks reasonable. The the more classical form with 2 BJTs (or BJT + MOSFET) in series would also work with not too much extra effort.
Part of this may be hidden in the "pre-regulator" part.
 
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Offline goleszek

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Re: EEZ Bench Box 3 (BB3)
« Reply #331 on: October 04, 2020, 06:08:17 pm »
The resistance module used for Labtool project reflects 1-2-3-4 sequences for value setting. However, it is not limited only to such steps. My initial assumption was to combine typical range from 10ohm to 10Mohm (1st decade on the board) and 0.1ohm to 20ohm (2nd decade, used as a power load), as indicated on the schematic. Additionally, to minimize resistance offset introduced by relay switches I added a bypass, which effectively reduces an overall error.

Finally, I hand soldered :( two identical decades with a higher range. If you plan to build your own, I strongly suggest using TH instead SMT relays - the assembly process will be much easier, as pointed by @prasimix.

For high-density packing and expected accuracy one should consider self-heating of relay coils - with 50 relays onboard and full activation it is more than 5..7W. During a long time operation, the resistance drift is kindly measurable.

The design uses TLE75008 relay drivers, although these ones can be replaced with 12-channels NCV7751, simplifying overall design, with higher availability.

The polymer fuses R38 and R130 can be replaced by shorts or typical (wire) fuse, which may reduce additional error due to temperature.
 
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Offline goleszek

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Re: EEZ Bench Box 3 (BB3)
« Reply #332 on: October 04, 2020, 06:19:20 pm »
@prasimix
-> One thing that is difficult to distinguish from the pictures, and what interests me is what the master MCU (STM32F4) directly controls.

Well, I used 10ms grid to communicate with each of the modules, independently of its number. If there was some action to be taken (like new data to be set, status check, readout, etc.), the F4 MCU was able to do it easily. In parallel, it supports LCD and onboard interfaces - with dedicated FIFOs and dual/triple video buffering, there was no lag observed.

The firmware runs on the FreeRTOS, with 1ms systick.
 

Offline IanJ

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Re: EEZ Bench Box 3 (BB3)
« Reply #333 on: October 04, 2020, 06:30:38 pm »
Hi Prasimix,

Is BB3 still on course for Oct. 6th shipping (Mouser).

Thanks,

Ian.
Ian Johnston
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Manufacturer of the PDVS2 & PDVS2mini
 

Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #334 on: October 05, 2020, 07:22:53 am »
For high-density packing and expected accuracy one should consider self-heating of relay coils - with 50 relays onboard and full activation it is more than 5..7W. During a long time operation, the resistance drift is kindly measurable.

Yes, relays heating is another thing I wanted to point out. Therefore, using a latching relay would make sense. Unfortunately their driving requires a lot more components, and it would be good if there was some integrated multi-channel driver, just as is the case with non-latching relays.


Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #335 on: October 05, 2020, 07:26:04 am »
Hi Prasimix,

Is BB3 still on course for Oct. 6th shipping (Mouser).

Thanks,

Ian.

Hi Ian, I really don’t know what to say. Looking at some other campaigns I see that everything needs to show up at the Mouser stock first to move on. This happened last week, for all items except individual DCP and DCM modules (don't know why since I sent them all together). I don’t know how synchronized CS and Mouser are when it comes to setting dates, but it would be high time it finally moved towards backers. Maybe it really happens tomorrow, which will be seen when the stock changes.
 
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Online Kleinstein

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Re: EEZ Bench Box 3 (BB3)
« Reply #336 on: October 05, 2020, 11:05:44 am »
One can use similar drivers for dual coil latching relays as for simple relays, it just needs twice as many. There are several types of power shift registers like tpic6C595 for 8 and also 16 outputs.  With latching ones heating at the driver is usually not a problem.
 

Offline goleszek

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Re: EEZ Bench Box 3 (BB3)
« Reply #337 on: October 05, 2020, 11:58:19 am »
The efficient and cost effective solution can be usage of typical non-latching relays, but driven from 2-step voltage regulator. During relay activation, the supply may go to nominal level (like 10V) and then be reduced to kindly 5V (or even lower, depending of release voltage). The overall power dissipation can easily be reduced in half and in a relay's coil by 75%...
 
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Offline exe

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Re: EEZ Bench Box 3 (BB3)
« Reply #338 on: October 05, 2020, 04:07:38 pm »
Resistor bypassed with a capacitor will be basically the same :). http://think.gusius.com/contactor-coil-power-saver/

The reason I didn't use it in one of my designs is that the capacitor needs to be reliable. If it dries out, the relay may stop activating.
 
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Offline goleszek

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Re: EEZ Bench Box 3 (BB3)
« Reply #339 on: October 05, 2020, 06:17:52 pm »
@exe
Yet for driving many relays (like a decade module) probably you need to replicate your circuit, which is not needed for previous one (i.e. when relays are activated from a GND side and sharing common supply)...
« Last Edit: October 05, 2020, 06:21:53 pm by goleszek »
 

Offline IanJ

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Re: EEZ Bench Box 3 (BB3)
« Reply #340 on: October 14, 2020, 10:34:43 pm »
Hi Prasimix,

Is BB3 still on course for Oct. 6th shipping (Mouser).

Thanks,

Ian.

Hi Ian, I really don’t know what to say. Looking at some other campaigns I see that everything needs to show up at the Mouser stock first to move on. This happened last week, for all items except individual DCP and DCM modules (don't know why since I sent them all together). I don’t know how synchronized CS and Mouser are when it comes to setting dates, but it would be high time it finally moved towards backers. Maybe it really happens tomorrow, which will be seen when the stock changes.

Good news!  got an email today.....it's being despatched.

Ian.
Ian Johnston
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Manufacturer of the PDVS2 & PDVS2mini
 
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Offline IanJ

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Re: EEZ Bench Box 3 (BB3)
« Reply #341 on: October 16, 2020, 04:24:15 pm »
First power photo below.

My initial interest is to use the BB3 help automate the testing of some of the products I make.....firstly where I set a power supply powering my products to various voltages and measure test points as I go along, and up the output voltage & CC setting as I go.
So, I got SCPI up & running on the BB3, got Keysight IO configured with the BB3 and my own GPIB app now talking to the BB3. So far so good!.....working out the box.

The very basics so far........
OUTP OFF, CH1
VOLT 15
CURR 0.5
OUTP ON, CH1

Ian.

« Last Edit: October 16, 2020, 05:26:32 pm by IanJ »
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Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #342 on: October 16, 2020, 05:47:54 pm »
Hi Ian, I'm so glad to see that your BB3 is working properly. Feel free to upgrade to the latest firmware v1.3.2 (instructions are available in Chapter 13) that the two modules use the entire screen. Also feeling free to try EEZ Studio, it's free. I'm also trying to finish a chapter on Node-RED integration that might be interesting to you.

Offline prasimix

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Re: EEZ Bench Box 3 (BB3)
« Reply #343 on: October 16, 2020, 05:56:38 pm »
I forgot to mention that MicroPython could be used for test automation, too. You can download few examples (not really about test automation :)) from here (or automate their download using EEZ Studio) and Chapter 16 covers "hello world" example where you can find how to make custom pages for interaction via its touchscreen.

Offline IanJ

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Re: EEZ Bench Box 3 (BB3)
« Reply #344 on: October 16, 2020, 06:29:26 pm »
prasimix,

With Keysight IO libraries I can query/response the BB3.....but from my own VB app I can make a valid connection but can't query the BB3 at all. I get an error responce.

I have written my own VB app but it uses an extensive GPIB library from PavelW. The IO library returns "MAV bit not set" when I try to query the BB3.
The developer of that library I remember he came across somebody else with the same issue try to connect to a DMM and offered the following repsonce at the time.

Quote
If the message is "MAV bit not set" then it is clear: your meter is not quite compliant with the 488.2 specification on the meaning of status byte bits. I explain. Polling the status byte is used here to check if the device is ready to send response, according to 488.2 this information is coded in the "Message Available" bit of the status byte, the bit 5 (so the default mask used is 16).
Keysight interactive IO works because it does not use any information from the status byte: when you hit "read" it calls the raw low-level read function which waits until it gets response.  But then once a "read" is issued the whole gpib bus will remain blocked until your meter is done with the measurement - very annoying if you have more than one devices connected, especially with high NPLC where it can take seconds to respond.  This software uses periodic polls to check if the data is available, before calling "read", in this way the bus remains available and the program is able to query two (or more) devices simultaneously.  This is the default configuration but it can be easily disabled on per-device basis (you may do it yourself or ask Ian to add checkboxes controlling the "enablepoll" flag for each device).  For a more elaborate version, the MAV masks can also be set individually for each device.

The above just my quick initial ideas as to the problem.........
I can work around it per what Pavel suggests and implement a checkbox in my app to enablepoll.........but just wondered initially your thoughts.

Ian.
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Offline IanJ

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Re: EEZ Bench Box 3 (BB3)
« Reply #345 on: October 16, 2020, 07:36:42 pm »
Hi,

I have a question regarding the usage of the BB3 (I am using Firmware V1.0 as shipped).
How do I change the default power up voltage/current (DCP405)...........seems to be 20Vdc/2.5A at the moment.

Also, and perhaps a future firmware tweak......I'd like to specify the minimum step change of the rotary encoder (say 0.1V, 0.01V etc), making it quicker to achieve the exact setting rerquired.

Ian.
« Last Edit: October 16, 2020, 07:41:37 pm by IanJ »
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Offline cadwal

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Re: EEZ Bench Box 3 (BB3)
« Reply #346 on: October 16, 2020, 08:33:50 pm »
A BB3 arrived here in Sweden today. Dropped off at my door just after lunch today having left Texas on the 14th.

Assembly now started  ;)

Oops, failed on step 2. Missing one J, have 5 or so extra L ...
« Last Edit: October 16, 2020, 10:06:08 pm by cadwal »
 
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Offline Kean

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Re: EEZ Bench Box 3 (BB3)
« Reply #347 on: October 16, 2020, 11:07:34 pm »
Hi,

I have a question regarding the usage of the BB3 (I am using Firmware V1.0 as shipped).
How do I change the default power up voltage/current (DCP405)...........seems to be 20Vdc/2.5A at the moment.

Also, and perhaps a future firmware tweak......I'd like to specify the minimum step change of the rotary encoder (say 0.1V, 0.01V etc), making it quicker to achieve the exact setting rerquired.

Ian.

+1 to both of these
 

Offline MaxZ

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Re: EEZ Bench Box 3 (BB3)
« Reply #348 on: October 17, 2020, 12:13:00 am »
Hi everyone,

@cadwal, @Kean: Kind of a solution for the power on settings: In the User Profiles Menu you have the option "Autorecall on power-on" (shown and described in the manual on page 51) which means it powers up with the settings you had the last time. Maybe another option that fits to your question: Settings->System protection settings->Force disabling of all outputs on power up.

Assembled my BB3 today. First impressions are pretty good so far. Here's what I noticed (positive first):
+ This thing is FAST. Boot time, UI response time and especially control and read out of the outputs. I've been sitting here for a minute turning the thing on-off-on-off just because it can do it so fast. The fast readout is impressive, too.
+ Manual looks well made. A lot of pictures of the UI with markings where to click what. Haven't used it a lot because IMO you shouldn't need a manual to get to know the basics about your device/tool/whatever. Manual is for the advanced and complicated stuff; the daily stuff should be self-explainig.
+ Many parts of the UI are well designed. Not only with regards to the previous point, but also with an eye on productivity. This was a big fear of mine; having a lot of features and a touch display is nice, but if it's slower to use than the good old 4 knob analog supply, it's annoying. Very happy to see that this fear did not become true for most parts.
+ Assembly was pretty straightforward. Big thumbs up for requiring only two types of screwdrivers, two types of screws (technically three if you count the two longer ones) and nothing else. No washers or clips or dunno what.
+ Packaging was pretty efficient. Everything protected and pretty much as compact as possible. This is the kind of details that give me the feeling that someone put effort and thoughts into it.
+ Putting those power supply modules into the bottom PCB was veery satisfying  ;D
+ Look and feel during the construction was very good. There're only very few minor things that could be improved in my opinion. Like it!
+ Thaaank you for the option to turn off the beep sounds. Otherwise I'd have desoldered the thing sooner or later.
+ Not directly related to BB3 itself, but I can't emphasize enough how much I respect the effort prasimix put in the fulfillment of the crowd supply campaign. I really hope that in the end you didn't loose money on this; that's really the last thing you deserve.

Now on the other side I also noticed things that could be improved in my opinion, and how I think it could be done. This time I try to put it in a meaningful order. While I'm typing this I realise it's getting muuuuch longer than I thought. Sorry for that. I really want to give some constructive feedback with this and hope that it is indeed useful (and not a much too long waste of time..).
At the very end I describe a more serious issue with my DCP405 modules. So in case you want to read this review another day (which I fully understand), I'd appreciate if you could take a look at the very last point (made it bold).

My Setup:
BB3 with 2x DCP405 and 1x DCM220. I'm still on v1.0 (reasons below). I guess some of the issues have been fixed in the meantime.

Getting started:
- So you get this note with half a dozen links. They are short but still, you have to type them by hand. I think you could include a QR code. There're too many links to include a direct QR code for every link, so I'd suggest to include one single QR code. It'll link to this document online. Then you can copy&paste (or even better: click) all the links you need or want to have a look at. Of course, not everyone wants to do this on his phone, nor can everyone do this. But those people can still type the links by hand. There's no disadvantage for them.

Access to information:
- Index in the PDF manual does not link to the pages. That's usually one checkbox at the PDF export and very useful. Another thing that's a bit confusing/annoying: Since the index does not link to the pages I enter the page number in my PDF viewer, f.ex. page 23. But this actually brings me to page 25. There's a mismatch; the x-th page of the document is not page with number x.
- I understand that this device is quite complex and powerful. However I had to click quite some time around before I found the assembly instructions. I'd have to take a more serious look at this and especially think about how one could make this easier before I can come up with concrete ideas.
- At one point I wanted to download the manual, because I had no idea where I'd find this information on the website. I found a "User Manual" entry in the index table at the top (reminder: I'm on my smartphone). Two download buttons are presented to me, for english and german. Okay so I click on the download button for the german one. But instead of getting the PDF I get to a new page whose purpse is apparently to give me "Download Details". And another download button. So I click on that and what do I get? well, still no download. Another page, this time providing me the very useful "Download summary". Which is basically the same thing as the two pages before but at least a different layout. Oh, and there's another one of those wannabe download buttons. You'll never guess what it does. It actually started a download - finally!
Seriously, I doubt its necessary or a good idea to let anyone go through that many useless (IMO) pages to open a manual...
- Another thing I particularly noticed on the page about how to do a firmware update. There's a short intro and then a looooong Linux secion with loots of code. Might be nothing complicated and really well described - that's not the point. I am not a Linux user (I guess like most people) and this was all I saw, even when scrolling down a bit. It's only after quite some more scolling that the Windows tutorial appeared. What if I have a Mac? do I scroll even more? The point I want to make is: obviously this page contains a couple very long sections. they have to be that long and that's fine. But it does not make the page more readable. If I have to scroll through an entire webpage that is multiple screen heights long, to find out if it even contains the information I'm looking for ("Firmware update with Windows"), I think the design is not the most user friendly.
Here's what I'd suggest for the mobile webpage. The page filling "global index" at the top can be hidden in a side menu. You know, the thing you acces with the button in the top left corner, that has thee horizontal lines as icon. This is important because the first thing I will see when opening the page can now be actual content and not a menu have to scroll through every time I click on a link. For the page itself I think a wikipedia-like design would help a lot. What I mean is that every section is at first collapsed and only its title visible. This is IMO a very clever way to allow quick navigation through a page with long sections - like wikipedia articles or firmware update guides. I'd immediately see 13.1 Linux, 13.2 Windows - perfect, tip to show that section and done.
- Speaking of firmware updates (does not quite match this section but fits perfectly after the previous point). You need different tools to upgrade different parts of the BB3? That's a bit disappointing... I hope you manage to get this all under one hood. Another issue IMO: you need to get this wired up to a PC...? Not sure if everyone has a lab PC - I for sure didn't have one for a loong time. What I'd love to do is this: Download the latest firmwares, drag them onto the microSD card, and the BB3 will update everything it finds a firmware for. No need to have a PC next to your lab supply, no need to download and configure any drivers or software according to multiple (!) tutorials. Just drag&drop, plug&play, done. (An even more fancy idea: since the thing has networking... You could let BB3 download new firmwares from the github release page  ;D )
- The complicated looking update procedure is the main reason why I'm still on v1.0. Download, drag&drop would've been a no-brainer but this is something I have to read through on another day. And while I absolutely appreciate that the firmware can be updated (meaning the device gets better and better over time), this makes me think that not as many people will update their BB3 and they won't do it as frequently as they would otherwise. HOWEVER, as I said, I haven't gone through the procedure, maybe it's already very quick 'n easy and half of my critic here is not right. Would be great! Still want that SD update  :P

Case/Mechanical/Assembly:
- I did not count the screws at the beginning but I know I missed one black screw when I was done. For some reason I have 6 of the silver screws left. Haven't found a hole where they'd be missing... That aside, I do think there should be 1 spare screw of both types, possibly even a third of the longer black ones. Since there're only 2 (3) different screw types, this shouldn't add too much cost and would help in case you loose one. Especially since quite a few BB3 users will open their case again to upgrade/change the modules - another chance to loose a screw. I thought about this when I realized there were no extra screws. And I really wished it when I realized I missed one. Don't want to blame anyone but I assembled it on a clean table with a clean, white floor underneath and I can not find it. So yeah, I'm probably blind.  :palm:
- The screws that hold the display are rusted...? Is that normal?
- About half of the threads in the case had paint in them which made it pretty hard to force the screw in. At least they won't get lose! Don't know if this can be avoided or not; just wanted to note it.
- The top case is slightly bended (higher in the middle); it can be pushed down about 2mm. Additionally, because it's screwed down on only two axes (left and right on the same place), the top part can be slightly pushed forwards/backwards and doesn't line up with the bottom part. Both things are purely cosmetic and no real issues but IMO this does not match the quality and feeling of the other parts. Take the bottom half; that one feels rock solid. Second reason for brining it up: both things could be fixed with one minor change I think: add 1 screw between front panel and top case, and 1 between back panel and top case. This should not only prevent the forward/backward fexibility but also hold the top piece down properly for an overall even more rigid feeling.
- The cable for the fan is about 3cm too short? I can't put it the way as shown in the assembly manual. If I put it from the connector down between the DC/DC converters and the heatsink, there's not enough length to put it against the backplate; it goes straight to the fan. (think of a triangle. hypotenuse is shorter than the other two sides together). Is this meant to be like this? Again, doesn't cause any issues I think but didn't seem right to me...
- A true detail: Every word on the front panel and on the module front panels has the first letter in upper case - as I'd expect it. Except of two things: SD card, which is fine IMO, and "Open hardware / open source". The second open in lower case does not look right to me; doesn't match the first one. You dont write "Dual sync buck" instead of "Dual Sync Buck" either. Not 100% sure if the "hardware" and "source" should be upper case, too, but at least the two "open" must be equal IMO. As I said, a detail, but one I'll see every single time I use the BB3 - which will hopefully be very often ;)

The Rotay Encoder
Now this one deserves its own section in my post because it was honestly the biggest disappointment. From your videos I can see that you don't use the encoder that much and prefer the keypad. I tried both and the encoder is really the thing that suits me the best. I'm sure this is very individual and every one will come up with a different habit that seems perfect to him/her. The most natural feeling way for me is touch the value, turn the knob. I don't use the keypad, I don't use the knob's push button to cycle through the values. What made it even more disappointing is that I absolutely believe that it could be possible to set values very fast. Like "I don't miss the 4 potentiometers from my analog supply at all" kind of fast. So here we go with my issues...
- For some reason the encoder does not sit straight. This means that the knob is too close to the front panel in one point and depending on how I turn it, scratches over the front panel. This feels really really cheap. I might even open it again and try to resolder the encoder to fix this.
- The knob sits rather loose on the encoder shaft. Being a big know makes it look even worse. Again, very cheap feeling to me.
- The encoder itself has no decent ticks but feels rather soft and spongy - again, a big knob doesn't help. Big knob = large radius = large lever arm => soft spongy ticks feel even more soft.
- The velocity control does not work at all for me. So I did play quite a bit with it and here's the issue (I think): the velocity increases only after about half a turn. If you turn the knob a quarter turn you won't get very far no matter how fast you do it. However, if I turn the knob with two finger, half a turn is the most I can turn it; usually more like 1/3 of a turn. If the knob was smaller, it would be more; maybe someone with bigger hands can turn this big knob a full turn but I cant. Same thing if you turn it with one finger by putting it on the side; you get about 1/3 of a turn.
So for my usual way(s) of using a knob velocity control is de facto inactive, making the knob de facto useless.
The only way to really get velocity control is to put one finger on the front of the knob and turn around (which includes slipping off). Then you can turn it a full revolution (before slipping of) and velocity control becomes veeery visible. But as described above; for the way I use a knob this is much too late.
Bottom line: please adjust the velocity control such that you can easily get across the range with 1/3 turns. I know it's possible. And I'm pretty sure some knobs I've used recognize when you to multiple quick movements (like you usually do with two fingers), and don't restart for every 1/3 turn at "zero velocity". One might say they have a bit more inertia.
- Even worse: If I have the velocity settings not at maximum (gets worse the lower you go), I can turn the knob and individual steps don't do anything anymore. I can turn the knob a whole revolution without changing the value. I think 1 tick should always do something.

Using BB3 and its UI (reminder: v1.0!)
- While I said above that I do think it's well made in most parts, it does make a ... convoluted? impression. Even though I know what is what, the overview with the 4 channels (I have 2x DCP405 + 1x DCM220) does somehow not look "clear", "stuctured". I honestly can't tell you why.
- When I tested it for the first time I turned on Channel 1 (first DCP405); fine. Tipped on channel 2 (second DCP405) - and I get a warning that its not calibrated. Okay, no worries, let's do it - but nooo I can't. This thing comes out of the box with a cal password. Okay, it's nice to have that option, but the few people who need this, will find the option because button for changing the cal password sits right next to the button for the main password - no chance to miss it. But everyone else (and seriously, how many people really want this?) has additional work with this. And especially during the very first "hands on", I shouldn't have to search through the manual for some default password... Even worse - I can't remove the thing? I can't leave the password blank when changing it? Might someone explain, why I, as a private user, would need to be forced to password protect the calibration routine?
- This point I'll bet that it's been fixed by now: There's the Settings point "Encoder & User sw" but I don't see any settings for the user sw? Maybe I'd have to read through the manual in detail but so far I haven't found any option or setting for that switch.
- I kinda mentionned it in the positive points but that beep thingy sounds "not good"; rather cheapish-annoying. Might be highly subjective; maybe other users like it.
- Now this is serious IMO. Using the DCP405 modules (happens with both of them). When I have the current limit at 8mA or lower and I short the output, it does not recover correctly after removing the short. Voltage was around 10V, but doesn't seem to matter. What happens is that the voltage stays slightly below the set value (f.ex. 11.5V instead of 12V) and the CC LED remains on. Current stays at the limit until I increase it to about 10mA or higher. Only then the current will drop back to 0 and I can decrease the limit again. MAYBE this a soldering fault on both of my modules...? One of them hat 2 capacitors that fell of the board, and a third one with a bad solder joint. Additionally I just noticed that that module must have at least one more bad solder joint, because the CC LED started flickering, and reacts if I knock on the case. Any ideas? That aside, the issue that it does not recover after entering current limiting mode is equally present on the other DCP405 module. I couldn't find any bad solder joints on that one but maybe I missed something?


Okay, finally, I'm done (or forgot the remaining points). If you read through all of this, I do hope it's useful. Thank you for all of your work, and in case all of this sounds too negative, you should know that I don't regret to have opted for the BB3 and would do it again.  :)

Max
 
The following users thanked this post: Kean, prasimix, Andrew McNamara

Offline IanJ

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Re: EEZ Bench Box 3 (BB3)
« Reply #349 on: October 17, 2020, 09:12:09 am »
Hi prasimix,

Trying to update firmware, not going so well.

I followed the Windows install for the DfuSE_Demo. Got it installed.
Powered up the BB3 in DFU mode (confirmed with blank LCD).
Usb cable connected Windows acknowledges a Usb connection (sounds).......but in Device Manager I have no "STM Device in DFU mode" listed.
Your guide tells me to install driver manually, but link is to the 32-bit Win7 version and as such won't install telling me to install 64-bit version......I couldn't find it. I have Win10.
So, I tried running ZADIG (I'm sure you will be aware of this app) and can confirm with the BB3 in DFU mode I see "STM32 BOOTLOADER" listed.......so I tried each of the 4 available drivers listed, but none of them give me "STM Device in DFU mode" in Device Manager.

So, at the moment I cannot upgrade the firmware.....very frustrating.

Btw, on normal boot of the BB3 I get "MASTER STM32 R2B4 - FAILED"...........is that normal?

Other than that, I do have an ST-LINK V2 and a V3.....can I use that direct on the MCU board via ST-LINK Utility, I notice there is an unpopulated header, SWD I presume....?

Ian.

UPDATE:
Got DFU mode in Device Manager now.....had to right click on STM32 BOOTLOADER in Device Manager and manually update drver from list of available. DFU mode driver was listed.
Firmware of my BB3 now updated.

Ian.
« Last Edit: October 17, 2020, 10:10:56 am by IanJ »
Ian Johnston
www.ianjohnston.com
Manufacturer of the PDVS2 & PDVS2mini
 


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