Need help to connect external 16 MB SPI Flash Memory on ESP32-WROVER Kit

markwj
Posts: 84
Joined: Tue Mar 08, 2016 5:03 am

Re: Need help to connect external 16 MB SPI Flash Memory on ESP32-WROVER Kit

Postby markwj » Sat Jan 20, 2018 5:35 am

Ritesh wrote:We had finalized to use 1.8 v supported external memory and also finalized to change default memory as external memory instead of internal memory.

So, with that we can use external memory as well as 4 MB PSRAM for more memory allocation purpose.

Let me know if need any help regarding this as e had already did it and started development using that configurations


How have you handled the 1.8v issue? Presumably using an external regulator 3.3v->1.8v for the external 1.8v flash. But, what about the CS line? On WROVER, all the VDIO domain GPIOs are used, so have to use a 3.3v CS line and level converter down to 1.8v. That is the approach we are using, but slightly concerned the propagation delay on the 3.3v->1.8v level converter will be too slow (5ns approx) for 40Mhz operation.

I _really_ wish Espressif would offer 16MB internal flash version of WROOM-32 and WROVER. 4MB is fine for one App, but when using the OTA feature, that reduces to 1MB (factory + 2x OTA partitions).

Ritesh
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Location: India
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Re: Need help to connect external 16 MB SPI Flash Memory on ESP32-WROVER Kit

Postby Ritesh » Sun Jan 21, 2018 5:45 pm

markwj wrote:
Ritesh wrote:We had finalized to use 1.8 v supported external memory and also finalized to change default memory as external memory instead of internal memory.

So, with that we can use external memory as well as 4 MB PSRAM for more memory allocation purpose.

Let me know if need any help regarding this as e had already did it and started development using that configurations


How have you handled the 1.8v issue? Presumably using an external regulator 3.3v->1.8v for the external 1.8v flash. But, what about the CS line? On WROVER, all the VDIO domain GPIOs are used, so have to use a 3.3v CS line and level converter down to 1.8v. That is the approach we are using, but slightly concerned the propagation delay on the 3.3v->1.8v level converter will be too slow (5ns approx) for 40Mhz operation.

I _really_ wish Espressif would offer 16MB internal flash version of WROOM-32 and WROVER. 4MB is fine for one App, but when using the OTA feature, that reduces to 1MB (factory + 2x OTA partitions).


Hi,

I am a software engineer but as we discussed with our hardware engineer regarding this issue and they had used 1.8 V supported external flash. But as per discussion with them they had also used voltage regulator as well to operate it.

So, Definitely, External Flash and PSRAM both will be working on 1.8 V. Also we need to enable external flash using EFUSE parameter settings which needs to update accordingly.

We already asked to Espressif Systems for 16 MB supported ESP32 module but right now there is no any plan like that. Right now, only 4 MB integrated modules will be supported with any ESP32 based module . They might give support for higher size flash memory variant in future but not right now. But if you had order for more than 5000 qty then they might design ESP32 based module for you.

Let me know if need any help from my side.
Regards,
Ritesh Prajapati

markwj
Posts: 84
Joined: Tue Mar 08, 2016 5:03 am

Re: Need help to connect external 16 MB SPI Flash Memory on ESP32-WROVER Kit

Postby markwj » Mon Jan 29, 2018 8:46 am

Ritesh wrote:I am a software engineer but as we discussed with our hardware engineer regarding this issue and they had used 1.8 V supported external flash. But as per discussion with them they had also used voltage regulator as well to operate it.

So, Definitely, External Flash and PSRAM both will be working on 1.8 V. Also we need to enable external flash using EFUSE parameter settings which needs to update accordingly.


I am interested in how you handle CS line? That must be a 3.3v line, but 1.8v flash is not 3.3v tolerant. So, how do you do that?

I have tried, using a level converter, and external flash works fine. But, PSRAM access then fails (with latest ESP IDF 3.x). Probably a timing issue, as 40MHz is pretty unforgiving and level converters have propagation delays of perhaps 5ns (or 1ns for the fastest I could find).

Ritesh
Posts: 575
Joined: Tue Sep 06, 2016 9:37 am
Location: India
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Re: Need help to connect external 16 MB SPI Flash Memory on ESP32-WROVER Kit

Postby Ritesh » Thu Feb 01, 2018 5:05 pm

markwj wrote:
Ritesh wrote:I am a software engineer but as we discussed with our hardware engineer regarding this issue and they had used 1.8 V supported external flash. But as per discussion with them they had also used voltage regulator as well to operate it.

So, Definitely, External Flash and PSRAM both will be working on 1.8 V. Also we need to enable external flash using EFUSE parameter settings which needs to update accordingly.


I am interested in how you handle CS line? That must be a 3.3v line, but 1.8v flash is not 3.3v tolerant. So, how do you do that?

I have tried, using a level converter, and external flash works fine. But, PSRAM access then fails (with latest ESP IDF 3.x). Probably a timing issue, as 40MHz is pretty unforgiving and level converters have propagation delays of perhaps 5ns (or 1ns for the fastest I could find).


We had used voltage level convertor to convert 3.3 V to 1.8 V. So, Let me check schematic and will get back to you with exact details.

We had also checked PSRAM. So you have to use it's supported Toolchain for that. Please confirm that from your end with ESP32 IDF 3.X
Regards,
Ritesh Prajapati

markwj
Posts: 84
Joined: Tue Mar 08, 2016 5:03 am

Re: Need help to connect external 16 MB SPI Flash Memory on ESP32-WROVER Kit

Postby markwj » Mon Feb 12, 2018 6:32 am

Ritesh wrote:We had used voltage level convertor to convert 3.3 V to 1.8 V. So, Let me check schematic and will get back to you with exact details.

We had also checked PSRAM. So you have to use it's supported Toolchain for that. Please confirm that from your end with ESP32 IDF 3.X


That would be helpful. From what I can see in Espressif code, PSRAM support won't work with external flash on non-standard pins. At least one part of ESP IDF will need to be changed.

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