[ESP32] New dev board

[mattyt]

I've been wanting a small ESP32 board for a while - now it looks like I'll be helping bring one to life! Just trying to gauge if anyone else has interest in such a board?

We're looking at something around the 30x20mm size but still breadboard-friendly (2 rows of 10 pins) - smaller than a Wemos D1 but with more pins. Some tradeoffs will be made; you can't break out everything from an ESP32 in 20 pins, but it's looking like it'll be quite a useful subset. Oh, and it will have LiPo battery charging too.

MicroPython will, of course, be a first-class citizen on this board.

The attraction of such a board for me is that many of my projects involve connecting something to the network but, usually, there are space constraints. This board is powerful enough to develop with but small enough to deploy, potentially with a shield where custom hardware is needed. But it means I would normally not need to lay out a complete board including the micro.

We're aware that it's a competitive landscape with the likes of Wemos and TTGO - it's impossible to compete directly on price. But the price/features/size balance is attractive to me, hopefully it will be to some of you too! Let me know if you're interested - and if there are any particular features you'd like.

[Roberthh]

Thta's the size of the WROVER module. And I do not see that they waste space inside.
It should have PSRAM. 4 or 8 MByte flash size should be OK. Since space is the limiting factor, it may be questionable whether a USB/UART bridge is required, even if you populate if from two sides You need 20x5 mm alone for a PCB antenna. Maybe a stack on board with USB/UART bridge, SD connector, flash support circuitry and reset switch could be foreseen.

[mattyt]

Thanks for the feedback!

Thta's the size of the WROVER module. And I do not see that they waste space inside.

The WROVER isn't exactly small for a module! Our design is based on the PICO D4 variant of the ESP32 which, in a 7x7mm package, contains flash, an oscillator and most of the passives. Also, since we are not breaking out every pin we can make some size reductions.

We also don't have...

It should have PSRAM. 4 or 8 MByte flash size should be OK.

...PSRAM. Do you find PSRAM necessary for many of your projects?

Right now there is little room left to route a RAM chip and, physically, the only location would be on the rear of the board. We'd have to increase the number of layers and shift some components to the rear, which does increase cost. But maybe it's worth having a more powerful variant of the board?

Since space is the limiting factor, it may be questionable whether a USB/UART bridge is required, even if you populate if from two sides

We had assumed that USB/UART was required; otherwise developing on the board is tedious. But USB/UART does indeed take room...

You need 20x5 mm alone for a PCB antenna.

We're going with a ceramic antenna for space reasons. The still take a large area of real estate but much less that a PCB antenna (around half the area).

Maybe a stack on board with USB/UART bridge, SD connector, flash support circuitry and reset switch could be foreseen.

It's an interesting idea that I've seen on at least one other board. But I'd prefer to keep it simple and cover the 80% of cases - if we can!

Thanks again for the feedback.

[loboris]

If the board is going to be breadboard-friendly the size is not too important (except for the width, so that more bredboard rows remains free).
What's wrong with the existing Espressif's ESP32-PICO-KIT Dev. Board which is 20.3x52 mm, available for 9.7 US$ (8.73 US$ if you register), 8.5 € from Mouser (EU).
Does making a 20 mm smaller board (with less pins) justifies the designing efforts if it doesn't offer any special features?

Feature you could add (I think it could be done on 2-layer board):
sd card socket (in SD mode as all pins cannot be routed to the board pins anyway)
better LDO than on ESP32-PICO-KIT
3.5x3.7 neopixel compatible RGB indicator (like SK6812MINI)

[OutoftheBOTS_]

@Laboris

better LDO than on ESP32-PICO-KIT

What is it you don't like about the LDO??

[OutoftheBOTS_]

We also don't have...

Roberthh wrote: ↑
Sun Sep 09, 2018 4:25 pm
It should have PSRAM. 4 or 8 MByte flash size should be OK.

...PSRAM. Do you find PSRAM necessary for many of your projects?

You don't need the psRAM on many projects. In fact I was using a board with psRAM but did set the BUILD for Laboris to activate the psRAM so wasn't using it and didn't even realize till 1 day I got memory error and was wondering how did I run out of RAM then learnt I hadn't selected to use psRAM.

I do note on 1 of your previous posts you were talking about a GUI and this definitely 1 area that the extra psRAM makes so much more possible.

[loboris]

What is it you don't like about the LDO??

AMS1117 used on ESP32-PICO-KIT has quiescent current of 5 (11 max) mA and the board can hardly be used for testing/using low power applications (with ESP32 in deep sleep). There are some other LDOs with much smaller qc (e.g. HT7833 4 uA (7 max), or some switching regulators).
Maybe not too important for most users, but most of the boards I've designed are designed for low power.

[OutoftheBOTS_]

What is it you don't like about the LDO??

AMS1117 used on ESP32-PICO-KIT has quiescent current of 5 (11 max) mA and the board can hardly be used for testing/using low power applications (with ESP32 in deep sleep). There are some other LDOs with much smaller qc (e.g. HT7833 4 uA (7 max), or some switching regulators).
Maybe not too important for most users, but most of the boards I've designed are designed for low power.

Ahh yes deep sleep. I have not used this feature so it never made my radar. I have liked the AMS1117 as to me it is the Sherman tank of LDOs.

Sorry Mattyt for the high jacking of your thread

[seonr]

[quote=loboris post_id=29973 time=1536512003 user_id=923]
What's wrong with the existing Espressif's ESP32-PICO-KIT Dev. Board which is 20.3x52 mm for 9.7 US$ (8.73 US$ if you register), 8.5 € from Mouser (EU).
Does making a 20 mm smaller board (with less pins) justifies the designing efforts if it doesn't offer any special features?
[/quote]

Hi loboris,

The pico-kit dec board is only 20mm longer, but also doesn't have on-board charge circuitry, so it's bigger with less features than this new board. Sure it has more pins, but when was the last time you made a project that required every GPIO the ESP32 has? That would be pretty rare for most people I think.

I definitely see the merits of having a fully broken out board in everyones toolset for initial proto-typing and testing, but rarely would you leave it in a project as a finished board I wouldn't think.

The plan is to also have shields for the board, so items like SD-Card, OLED screens, extra flash and maybe even a Battery backed RTC shield are all possible... maybe even an uber shield that incorporates a bunch of stuff for those that need them.

Cheers,
Seon
unexpectedmaker.com

[mattyt]

If the board is going to be breadboard-friendly the size is not too important (except for the width, so that more bredboard rows remains free).
What's wrong with the existing Espressif's ESP32-PICO-KIT Dev. Board which is 20.3x52 mm, available for 9.7 US$ (8.73 US$ if you register), 8.5 € from Mouser (EU).
Does making a 20 mm smaller board (with less pins) justifies the designing efforts if it doesn't offer any special features?

For me a smaller board is itself a 'special feature'. I understand that may not be a feature for everyone.

Feature you could add (I think it could be done on 2-layer board):
sd card socket (in SD mode as all pins cannot be routed to the board pins anyway)
better LDO than on ESP32-PICO-KIT
3.5x3.7 neopixel compatible RGB indicator (like SK6812MINI)

Excellent suggestions! I'm quite keen to get some sort of RGB LED on the board but it didn't quite make the first rev. An SD card is very helpful at times though space constraints probably means we'll have to put it on a shield.

I wasn't aware that the PICO-KIT LDO wasn't particularly efficient. I'm actually really interested at looking at the board holistically in terms of power use - LED's, USB/Serial, the charge circuitry etc. I'm keen to push the use of the ULP for a couple of low-power projects but without board support it'll be wasted. Again, couldn't get there for rev 1.

Thanks Boris!