[wmlavender]

There are many of us that work with scientific instrumentation that has to retain compatibility with 5 volt logic levels. Many labs have equipment that is over 50 years old and which is still in use. Suppose you tell a scientist that they have to replace a working instrument built in the 1960s with a new one that costs over $250,000 only because it does not use 3.3 volt logic levels. They are going to laugh at you and say that they want to keep using the old instrument.

So having cheap and easily available electronics that can still interface with 5 volts can be very useful to some of us.

[IshKebab]

You can still interface with 5 volts using a level shifter. Which is exactly what this board uses so the 3.3V ESP32 can talk to the 5V Renesas chip.

[wmlavender]

I work for several beamlines at the Advanced Photon Source. There are probably far, far over 1,000,000 electronic signals at the whole APS facility that use 5 volt signaling. So almost any level shifting will be to embed 3.3 volt signals in a 5 volt world. It is simpler to buy equipment that has already done this.

[IshKebab]

Ok but this is an Arduino designed for hobbyists, not for scientists at the Advanced Photon Source.

[wmlavender]

No doubt. But lots of Arduinos have been used in scientific experiments because they are inexpensive and easy to work with. So the choices made in Arduino-like boards do affect us.

[gmiller123456]

I doubt interfacing with 80 year old lab equipment is the target market for this board. Though I can see supporting the existing shields and interface being a design goal. But there's already a lot of ESP32s in use today using a variety of methods to interface to 5v devices without including a whole other microcontroller.

[spoiler]

I never realised older scientific equipment even has interfaces for plugging in third party tools! I'm curious, how often do you actually have to make stuff that interfaces with older lab equipment when developing new equipment. And a follow up question would be: is this something you do in house, or do you sell this as a service/products?

And if you're allowed to go into detail, can you give a high level example of this (too low level might go over my head).

[wmlavender]

Yes, most scientific lab tools have some way of communicating with third-party tools. We tend to shun tools that do not, although some vendors are perplexed and/or annoyed by this. No one vendor carries everything you need.

There have been several generations of scientific instrumentation standards used for connecting products from various companies together.

Some take the form of Crates, which can contain individual modules that you plug into the crates. For example,

  *NIM* - <https://en.wikipedia.org/wiki/Nuclear_Instrumentation_Module> - Started in the 1960s, but there is a ton of these modules still in use.  Lots pictures of NIM electronics can be found by doing a Google Image search for *nim electronics*.

  *CAMAC* -<https://en.wikipedia.org/wiki/Computer_Automated_Measurement_and_Control> - Started in the 1970s, but is mostly obsolete and removed now.  It was the first bus standard to provide for computer control of instrumentation, mostly by PDP-11s and then later VAXes.  It could send you 24-bit data words at the blindingly fast speed of 1 MHz.  Some pictures of them can be found by a Google Image search for "*camac electronics*.

  *VME* - <https://en.wikipedia.org/wiki/VMEbus> - Originally created in the 1980s as a computer bus for m68k computers.  But it found a new, far faster life as a scientific instrumentation standard.  A number of bus standards like VXI have attempted to claim the throne of VME, but VME is still widely in use.  Some pictures of this can be found by a Google Search for "vme beamline electronics*.

The other major form factor is cables

  *RS232-RS485-etc* - <https://en.wikipedia.org/wiki/RS-232> - An ancient standard started in 1960, but still widely in use.

  *GPIB or IEEE488* - <https://en.wikipedia.org/wiki/IEEE-488> - Originally created by Hewlett Packard, but still widely in use.  Seems to be on the decline these days.

  *USB* - <https://en.wikipedia.org/wiki/USB> - The new contender for the throne.  Its use is growing by leaps and bounds with each passing year.  Bear in mind that one of the largest uses here of USB is for USB-to-Serial dongles that let us plug in the RS232 and RS485 stuff we are still using.

  *Ethernet* - <https://en.wikipedia.org/wiki/Ethernet> - Using mostly TCP and UDP, but not always.  This is the other contender for the throne.

  *Short-lived standards* - There were a variety of other standards that had short periods on the stage, like parallel ports, Firewire, SCSI, proprietary bare ribbon cables, etc.  Most of this has gone away, except for the proprietary ribbon cables *(sigh)*.

I do most of my work these days for two organizations, namely MRCAT <http://mrcat.iit.edu/> and BioCAT <https://www.bio.aps.anl.gov/> which both make use of X-ray beams at the Advanced Photon Source <https://www.aps.anl.gov/About/Overview>. The APS is a 1.1 kilometer electron storage ring, which produces high intensity X-ray beams at 70 sectors around the ring. My employers use 3 beamlines at 2 of those sectors for materials research and for biophysics.

You can find a lot of beamline pictures by doing a Google search for advanced photon source beamlines.

[comboy]

Level shifting is trivial though.

[wmlavender]

Not if you are doing it for 10,000 signals or more.

[comboy]

What do you mean? You need one level shifter per IO pin. You can get something like TXS0108E for e.g,, that's 8 pins and it will cost you less than $1. It can do millions of signals per second, but if you don't care about speed single mosfet will do.

[wmlavender]

It sounds like you are suggesting that we build our own custom circuit boards. The people that I work for do not manufacture our own circuit boards. We largely do not have the expertise to manufacture our own circuit boards. We are not electrical engineers.

The Advanced Photon Source has electrical engineers, but we are not part of the Advanced Photon Source. If we go to the Advanced Photon Source and ask them to build boards for us, they would probably quote a price and ask us if we have the budget to pay for that. Or they might say that they are too busy to do it for us. That would be especially likely now since the Advanced Photon Source is in the middle of a major upgrade.

In the end, it is better for us to find vendors that make data acquisition equipment compatible with 5 volt logic and buy stuff from them. That is probably true for most of the organizations that make use of the Advanced Photon Source.

[comboy]

I mean, you have to connect the MCU to your thing somehow, that's building a circuit, so you just insert the level shifty thingy between. But I have no clue about your seemingly highly specialized use case (which, why arduino of all things), so presumably you know better.

[wmlavender]

If I can find a 5 volt compatible device that does what we need, then why would I even bother looking at 3.3 volt devices?

[throwawaymobule]

I'm sure I just haven't looked hard enough, but I'm surprised nobody's put a few of those level shifters in an arduino shield yet, to convert the whole board to arbitrary voltages. The analog pins might be a little harder.

[crote]

Level converting is surprisingly difficult when you have to deal with both push/pull outputs, digital&analog inputs, and pullups for open-drain buses. In fact, I am not aware of any level converters which can deal with all of that.