which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

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kolban
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby kolban » Thu Jan 05, 2017 1:04 am

Howdy folks,
I'm slow of thought ... and am trying to decode this thread ...

What I think we are saying here is that there is the rumor/existence of a new ESP32 module that has 4MBytes of something called "PSRAM" (see https://www.jedec.org/standards-documen ... mory-psram) which for the purposes of this discussion mean "RAM" (until I hear otherwise). The practical up-shot of this would be a dramatic (8x) more RAM available to our applications than with the current 512K of the ESP32 by itself.

Beyond that, we are still waiting to hear about availability, price, power consumption and other technical specifications. Please correct me if I have mis-understood.
Free book on ESP32 available here: https://leanpub.com/kolban-ESP32

ESP_Sprite
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby ESP_Sprite » Thu Jan 05, 2017 3:02 am

That's about right. I expect a module with RAM to be on the market simultaneously with the release of the revised ESP32 silicon; the first silicon has some bugs that make integrating PSRAM into the memory map tricky at best and impossible at worst. At that time, esp-idf will also get code to make sure you can just mmap() and get the PSRAM memory back when applicable.

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loboris
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby loboris » Thu Jan 05, 2017 10:47 am

I think we can hardly expect 4 Mbyte (ps)RAM on ESP32 module.
The best candidate for external RAM with ESP32 (that I know about) is SPI SRAM like
http://www.microchip.com/wwwproducts/en/23A1024
and it is only 1 Mbit ( 128 KByte)
I'm very interested to hear form Espressif if they have some other solution.

ESP_Angus
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby ESP_Angus » Thu Jan 05, 2017 10:31 pm

loboris wrote:I think we can hardly expect 4 Mbyte (ps)RAM on ESP32 module.
It's always good to exceed expectations, I guess. ;)

The SPI PSRAM on the ESP-WROOM module will be 4 Mbyte (32Mbit). This module has 4 Mbytes of SPI flash and 4Mbytes of SPI RAM. More details will be available when this module is closer to release, thanks everyone for being patient.

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loboris
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby loboris » Fri Jan 13, 2017 5:33 pm

I understand it is hard to give more dailes about feature not yet ready for production. But it would be very usefull for product development planning to know a little bit more about what we can expect from SPI RAM addition.
Will it be available as heap/stack? What kind of performance (speed) can we expect from SPI RAM?
I'll be patient, but, as the information already apeared, could you give us more info?

ESP_Sprite
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby ESP_Sprite » Sat Jan 14, 2017 2:48 pm

The RAM will be usable as DRAM only, not IRAM. In practice, this means that you can use it as data memory for heap and stack, but you can't run instructions from it. We will add options to add this memory to the global heap/stack pool; the plan for now is to also add different strategies to automatically try to decide what should be allocated where. (Apart from that, you can also allocate a chunk of memory specifically from external RAM or internal memory, in the same way you can already specifically grab a chunk of IRAM if you so wish.)

For speed, if memory serves we had the RAM working in quad-IO mode on 40MHz; that would mean a throughput of 20MByte/second. In theory, we can get it up to 80MHz (=40MByte/second) but because we found a bug in the first silicon, we dropped the effort to get there; we'll probably pick it up again when the new silicon arrives. In practice, this speed may be higher because all accesses get cached in the flash cache; if you have a cache hit, you may get your data back within one clock cycle.

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loboris
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby loboris » Sat Jan 14, 2017 10:15 pm

That is exactly the information I've needed. It opens the whole new word to ESP32 development.
Great work Espressif!

ichannel
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby ichannel » Wed Mar 15, 2017 9:05 am

Hi

We are running into bottleneck of DRAM and would like to add an external SRAM or PSRAM. There has been the mentioning of an 4 MByte SRAM used in the new module. Can we have more information about it, like the vendor, part number, etc..

Thanks

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rudi ;-)
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby rudi ;-) » Wed Mar 15, 2017 9:22 am

ESP_Sprite wrote:
In theory, we can get it up to 80MHz (=40MByte/second) but because we found a bug in the first silicon, we dropped the effort to get there; we'll probably pick it up again when the new silicon arrives.

hi Jeroen,

some news?

can you share your test with ESP-Wrover ( silicon v1 )

thank you

best wishes
rudi ;-)
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ESP_Sprite
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Re: which new "esp" 8 pin ic is this on the new esp32 modul? ;-)

Postby ESP_Sprite » Thu Mar 16, 2017 5:55 am

Edit: I'm going to be a bit more vague, not to create wrong expectations. Basically, we're still validating it.

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