Latest on ESP32

If I were manufacturing this in China, that might be a win, but the components are too expensive here. The CP2102 is very expensive here, who knows how the Chinese do it. If you look close, a lot of them don’t have any markings. The micro USB connector is expensive in my quantities and is an expensive part to assemble because of the thru-hole tabs needed for strength. When you add up the cost of the parts it’s not a big savings.

With the nodeMCU I get a tested functioning unit. There is also an issue with the antenna being mounted directly to the main PCB. The recommendation is to have it hang off the PCB and I don’t have any space to do that. The nodeMCU raises it up off the main PCB and it works pretty well.

Then there is the enclosure. Moving the location of the usb plug may seem trivial, but it’s a big deal. That part of the enclosure mold is an interchangeable cam assembly, and would require a whole new assembly. The ESP32 nodeMCU itself has necessitated moving the slot and the AC plug, and I’ve already started the process of having a new cam assembly built.

You are right. If I were anticipating selling a higher volume, the economies of scale would prevail, but at this point I don’t see a clear advantage. I haven’t tried to buy the ESP32 devkits in quantity yet, but I do have the ESP8266 devkits custom made with ESP12S modules for FCC compliance. They are cheaper than you might think and much better quality than the usual fare.

For my boards, I don’t bother with having USB on-board. With two transistors and two resistors, I can have an auto-reset circuit that’ll let me easily program my board using one of these: That adapter can supply 3.3V and 5V. I use 2x3 header holes on my PCB to break out 3.3V, GND, RX, TX, RTS, and CTS. For prototype units, I’ll solder in a male or female header but for bulk programming boards, I just push one of these onto the holes and hit go: It programs exactly the same in Arduino IDE as a dev board with onboard USB.

Once my code progresses a little, I usually add an OTA update feature to avoid having to open the case after initial programming.

For the PCB antenna, I use a keepout area in Eagle to prevent any copper under the antenna area and I haven’t noticed any issues. Modules are available from digikey for under $3 and some allow for external antennas (< $4) if signal range is an issue.

I used OshPNP for USA fab and they were great to work with and very supportive of small run just-above-hobby-level jobs.

Sounds like a plan. As an open software/hardware project, I think the homebrew folks appreciate the convenience of the nodeMCU. The USB also serves as a field debug as the IoTaWatt pushes out additional diagnostic information via Serial. With USB anybody can connect and use a serial monitor like Putty and a standard cable.

The field upgrade in IoTaWatt is custom and uses a signed release blob for security, but if for some reason a unit gets bricked, it can be reflashed without opening the case using a common USB cable.

Good to know about the success with a keepout on the PCB. Maybe someday.

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Just wondering if there would be an update on the esp32 development?
Units with double the inputs would free up the needed space in my electricity cabinet :smile:

Just to ask… any hope of integrating in battery support to ride through short outages? I have an awful kludge of a way to do it, but it is a shame to not do it “right.”

great work, congratulations.
are you thinking in using an esp32 with ethernet port?
is the new case din rail compatible?
i’m working on a project for a cliente and i’m thinking to buy 150 iottawatt (i have already purchase 2 (two months ago)) but wifi is a problem for this project.
best regards

No Ethernet. While ESP32 has an Ethernet capability, it consumes so many of the I/O pins it is essentially mutually exclusive with SPI, which is fundamental to IoTaWatt architecture.

The ESP32 fits in the existing ESP8266 enclosure, with another connected by a ribbon cable when using the additional 14 inputs.

This is great, any release date or plans to make the schematics public? I’m looking at buying an Iotawatt but would like to get the esp32 version now! :smiley:


I would love to replace one of mine with the ESP32 versions when available— all inputs are currently used, and it seems to reboot frequently due to a diminished heap.

But, for 90% of users it is unlikely to make a significant difference.

Just to ask the question, if you could get a grant to cover maybe half the cost would your outlook change on it at all? I know of at least one private foundation that supports sustainability projects and the IoTaWatt might be eligible.


Would a Kickstarter type approach help with the regulatory testing once the design is finalised?

You have the track record of delivering reliable product (and supporting it) iso it would be a highly credible project.

Kickstarter or equivalent would eliminate the risk of not recouping your investment - if enough people aren’t interested in pre-paying for a unit the project doesn’t proceed.


Hi Bob :

Great Stuff. Just ordered an IotaWatt system. Several items :slight_smile:

We are early stage folks in this and would like to get some advice.

We will likely be sending the data to our cloud in AWS - and are using MySQL. We can do GETs from the IoTaWatt - but since we do need to have a webserver, are we restricted to Influx / OpenMonCMS / SolarPV ? Is there a way to have a generic webserver where we just insert the URL for teh data to be sent to ?

How can we get near “real time” data - say every 1 or 5 minutes - will the Query API be able to do that for us ?

I see that possibly the ESP32 development will help the HTTP issue - but will we able to install our own webserver in there or a generic webserver with a post URL ?

When do you think that you will have the ESP32 development complete ? At least dev versions - not certified by UL and also the final certified versions ?

Thanks so much


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There is a REST query API.

Those are the supported uploaders.


Yes, you can query with 5 second resolution.

The firmware is open source. You can modify it as you please.

I have not committed to releasing that project. There are a lot of factors to consider.

Thank You Bob… We are looking forward to the ESP32 release.

is it available esp32 source code?
i’m trying to implement with esp32 olimex (ethernet) and it will be more easy start with esp32 code and not esp8266 source code.

Wired ethernet is a non-starter with IoTaWatt ESP32. The PHY requires practically all of the pins used for the SPI and I2C. While the I2C can be remapped, the SPI cannot. There are simply not enough pins to support both SPI and PHY.

If you want IoTaWatt with wired ethernet, I’d say port the code to an ARM chip.

first of all thank you for your time and for the project.
But, why not to change to this type of ADC ADS7138-Q1 that uses I2C protocol and solve the problem with SPI ports?
best regards

Looks nice on paper, The devil is in the details.

thak you so much.
I will try to test ADS7138-Q1.
is it available on repo ESP32 code for Iota?
best regards

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