Alternate Compatible Dev Boards

[Ryan Parle]

A few years back i put this project together on a bread board, everything worked and i just used it as it was, besides the odd issue caused by the odd component becoming dislodged it has been very reliable. However due to its fragility it has only been used during known good weather and recently I have been more driven to do a better job of connecting the hardware.

I would like to build a PCB for this project that is does away with all of the "breakout board style sensors" and the majority of through hole components instead having all the sensors directly mounted on boards of my own design and using mostly SMD components, I would also like to change the location and style of connectors for the external sensors such as wind speed, direction and RG11 rain sensor for more rugged IP rated types and use either jumpers or dip switches to change between the D2, R3, R4 & R5 options so that sensor types can be swapped without getting the soldering iron out.
I spent a few hours developing the schematics and then got to placing components on the board, which was when I realised that the devkit board libraries I had imported were for a 38 pin variation. I understand that this of course is not pin compatible with the original PCB design but I wonder if it would still be suitable for the project providing that I reassign the pinouts correctly.

The board that i have used in my schematic is linked below:
https://www.mouser.co.uk/ProductDetail/Espressif-Systems/ESP32-DevKitC-32UE?qs=GedFDFLaBXFguOYDKoZ3jA%3D%3D&mgh=1&vip=1&utm_id=20797887765&gad_source=1&gclid=CjwKCAiAg8S7BhATEiwAO2-R6qUOf3hfz5-HWdsTyP-cXBu0j2czDAKptVPSZ24z-17P2jrrPYj-YxoC2ooQAvD_BwE

If this is not suitable please can you advise on the specific requirement of the ESP32 module for this project.

This also got me thinking about ditching the devkit all together and mounting the ESP32 module directly to the main board and programming using an ISP header.

Once complete I will of course be happy to contribute my designs to the rest of the community here as an alternative build option

[brownrb]

Hi

Of all the "myprojects" this is one project where the pins used is vitally important, so you will need to use the same pin designations. If you are well versed, then yes some pin changes can be made, but be wary because using "other" pins not used in this project can make or break this project.

A lot of early work in prototyping (months) was spent checking what pins could or could not be used.

The project requires an ESP32 dual core chip with multiple timers, and so that excludes a LOT of other esp32 chips (the rule is esp32x <> esp32y). The 30pDev module was finalised because on most of the 38p boards: They include pins that really you cannot use (as there are tied to the Flash memory).

Be very wary about what pins you choose because even on the 30p version there are some pins that one cannot use, or pins that are input only and cannot be used as in/out pins. One can be certain to experience intermittent crashes when using these extra pins. Been there, done that, learnt my lesson. (Accessing controllerdata during loading a web-page from flash is pretty much living in my head rent-free).

Some include additional flash memory, some do not.

I have 0 intent to move away from the ESP32 30p dev module. Its still widely available and at a very reasonable cost (on aliexpress for example).

Oh, the link did not work.
I do notice that in general WiFi on the ESP32 is fairly good. If I using the unit a fair distance away (100m+) I would opt for one that supports an external antenna, but I know may users run this at up to 150m away without issue.

Oh, and I final thing I can add, if supporting windspped/direstion sensors that rely on 12v, I would make sure that the 12v is very stable with little or no voltage drift, because some of those analog sensors become inaccurate unless the 12v is a very stable 12v.

Regards
Robert

An answer goes something like this: Not my own words.

Usually the extra exposed pins are actually used internally, so it's highly recommended to leave those alone unless you know what you're doing. Since you're asking what the difference, go for the 30 pin version so you don't have to worry about this problem. The 30 pin version should be good enough for everyone, except for some very specific use cases. If you ever find yourself in such a use case, you will know exactly what those pins are for and what the difference between the boards is.

I'm no expert, but I think the extra pins are hooked up to the "internal" memory of the ESP. The memory isn't actually part the ESP chip, but it's part of the ESP module (the metal cap has several components underneath). If you mess with the extra pins the ESP won't be able to read it's memory properly, which will likely result in problems.

[Ryan Parle]

Thanks Robert for the informative reply, I guess i should make it clear that i don't really wish to mess with pin designation, more to transpose the pins to a dev board of a different layout, so if in your design a sensor is connected to GPIO 18, then i would also connect to GPIO 18, however these pins may have a different physical location on the devboard.
I don't intend to make use of the additional pins that are broken out on the 38 pin version.

incidentally i am now leaning more towards the idea of using the ESP32 module directly on my board and not using the devkit at all

PS i'll update the link in the first post, somehow i only copied part of the url

[brownrb]

Hi Ryan
I was only commenting on what might be background info that you might find useful :-)

I like the idea of using SMD, its something I never got round to based on "ease of putting something together" helping users get started with little effort.

In a lot of modules for ESP32 boards, I understand that some use an external flash chip. If this is the case with your design, I would probably recommend using 8GB instead of 4GB as most board modules use (one can never have enough memory).

Regards
Robert.

[Ryan Parle]

Do you mean Gigabyte or Megabytes? I haven't seen any ESP WROOM32 modules with memory in the Gigabytes.

[brownrb]

my mistake.