ESP32 in Pre-Order

RogerClark wrote:Just a thought, but is there a breakout board for the ESP32 that can be bought separately

Its a bit unclear what the modules will look like, I’m not sure if the images shown on AliExpress are just a mockup

Anyway, I found this kicad symbol https://github.com/morganrallen/esp32-kicad/

But whether it matches with what I have ordered from AliExpress is hard to know at the moment.

I guess I could take a punt and design a breakout board using that footprint.

Yes, the breakouts were provided by Espressif as part of the Pre-Christmas Beta shipments.
(Remember that I was this little guy crying under the Christmas tree because I didn’t received one of those gifts … )

I presume that when real production start, Espressif will make the breakout design available, if it is not already.

If there could be a “dream” breakout board for ESP32, in addition of USB UART and RST, I would like to see a level shifters for the old 5V world.

Are there any recommendations for level shifters for high speed communication? With brute force resistor chains the speed is limited in kHz range. What could be used for 20 MHz communication?

Cheers, Ollie

Simply use traditional MOSFET method :

Image

Ollie wrote:If there could be a “dream” breakout board for ESP32, in addition of USB UART and RST, I would like to see a level shifters for the old 5V world.
<…>

Hi Ray,
But here, we are talking about ESP32, so I don’t think there is a single pin that are 5V tolerant …
The small 4 channel shifters, that you’ve provided link for, are in fact 4 times the schematic I’ve provided.
So, about cost issue, it is maybe relevant to put it on such breakout board since they are only taking PCB real-estate and can be overriden when not needed by simply avoiding the mosfet and pullups and placing a 0R shunt instead. Still the cost of such mosfets is less than 3 cents.
Of course, there is no need to provide such circuits on every GPIOs, but only relevant ones, such port for OneWire, some Serials but maybe only one.
So, it all depends of the projects. For example, on my F405, I’ve done it for OneWire, simply because it is enhanced the signals on long wires.

martinayotte wrote:Hi Ray,
But here, we are talking about ESP32, so I don’t think there is a single pin that are 5V tolerant …
<…>

The 2N7000 is proven technology for level shifting. Any comments about the TI TXS0108E. It is not too expensive – lot of 5 costs $3.70. With 8 channels per chip, it is $3.70/40 per channel, around $0.09. My preference is to use the chips instead of large number of components.

Cheers, Ollie

Ollie wrote:<…>My preference is to use the chips instead of large number of components.
Cheers, Ollie

I agree with Ray

The world has moved on… 3.3V is the norm.

I see no point in having level shifters.

If someone has a requirement to use a 5V technology, the would need a separate OneWire to 3.3v converter as part of their OneWire interface.

In much the same way as for other transmission line technologies.

RogerClark wrote:I agree with Ray

The world has moved on… 3.3V is the norm.

I see no point in having level shifters.

stevech wrote:RogerClark wrote:I agree with Ray

The world has moved on… 3.3V is the norm.

I see no point in having level shifters.

madias wrote:stevech wrote:RogerClark wrote:I agree with Ray

The world has moved on… 3.3V is the norm.

I see no point in having level shifters.

racemaniac wrote:
<…>
lol, have the exact same lying around, haven’t needed them yet

mrburnette wrote:Yep. I have 49 in a box and 1 on the bench gathering dust. But that the way it goes … buy a bunch of something and be assured you will not need it. In my case, I gather up older, unused stuff once a year and go down to Stone Mountain Hamfest to recycle same. Sometimes it works and I take the proceeds and buy more “maybe” things. My hobby is my personal way of helping out in the global economic crunch!

WereCatf wrote:
<…>
I heartily approve of recycling electronic stuff instead of throwing away.

I quite like the DMA-engine on the STM32, it sure makes bulk-transfers over SPI so much faster; ESP8266’s 64-byte FIFO just can’t quite compare, unless you’re writing patterns of 64 bytes or less, and even then you can’t queue it to happen in the background while your code is doing something else. I tried googling for it, but I can’t seem to find any information on whether the ESP32 has a DMA-engine capable of driving the SPI-bus

I really quite want a combination of both the STM32 and ESP8266 — built-in WiFi, 80MHz (or higher) SPI-bus and lots of RAM, but also lots of I/O and a proper DMA-engine.

WereCatf wrote:I quite like the DMA-engine on the STM32, it sure makes bulk-transfers over SPI so much faster; ESP8266’s 64-byte FIFO just can’t quite compare, unless you’re writing patterns of 64 bytes or less, and even then you can’t queue it to happen in the background while your code is doing something else. I tried googling for it, but I can’t seem to find any information on whether the ESP32 has a DMA-engine capable of driving the SPI-bus

I really quite want a combination of both the STM32 and ESP8266 — built-in WiFi, 80MHz (or higher) SPI-bus and lots of RAM, but also lots of I/O and a proper DMA-engine.

racemaniac wrote:I keep wondering why everyone keeps looking at dma just for the speed. It not happening on the cpu is for me the most amazing part. I’ve got code steering a 144 neopixel string at 215 fps, basically continuously sending it data (>99% of the time), and hardly using any cpu cycles since it’s all DMA XD.