ESP32 Forum

Background:
I have been designing a board that uses the WROVER, but it has come to my attention that it does not have all the certifications that the WROOM has. This means that I'm needing to either switch to the WROOM or certify the WROVER myself; I prefer not certify the WROVER.

Problem:
The WROVER has an internal PSRAM while the WROOM does not. I have tried to find a 3.3V PSRAM, but there are not many available. The few that are available are too expensive.

Has anybody tried an implementation using an external 1.8V PSRAM and a high-speed bi-direction level translator? Looking at both the schematics of the WROOM and WROVER, it appears that I could connect a level translator / PSRAM to the WROOM the same way the WROVER is designed.

Any ideas on how to implement a 3.3V or 1.8V external PSRAM would be greatly appreciated!

Also, does Expressif have any intention on making a WROOM with a 1.8V Internal Flash Chip so we can design with 1.8V PSRAM externally?

Thank you!

What certificate do you need? How big is your volume?

Not sure if it is much help, but I tried and failed this route. The PSRAM clock is different (delayed) from the FLASH clock, and both run at high speed (40MHz). Adding a level converter, with further propagation delay, just wasn't reliable.

Our project switched back to using standard modules. Analog Lamb have WROOM32 modules with PSRAM, as well as WROVER modules. Both are available with 4MB/8MB/16MB flash chip sizes. They are pricey, though, and I'm not certain of the certification (if any).

WiFive wrote:What certificate do you need? How big is your volume?

I am needing the Industry Canada Certificate. The WROOM has it, but the WROVER doesn't; which is surprising. My EAU would be upwards of 5000+ pieces.

markwj wrote:Not sure if it is much help, but I tried and failed this route. The PSRAM clock is different (delayed) from the FLASH clock, and both run at high speed (40MHz). Adding a level converter, with further propagation delay, just wasn't reliable.

Our project switched back to using standard modules. Analog Lamb have WROOM32 modules with PSRAM, as well as WROVER modules. Both are available with 4MB/8MB/16MB flash chip sizes. They are pricey, though, and I'm not certain of the certification (if any).

Was it a delay issue, a signal integrity issue, or a combination of both? I had read somewhere on the forums, that a chip manufacturer is working a 3.3V PSRAM, but I'm worried about the supply chain of that part.

Tyler@FB wrote:Was it a delay issue, a signal integrity issue, or a combination of both? I had read somewhere on the forums, that a chip manufacturer is working a 3.3V PSRAM, but I'm worried about the supply chain of that part.

The level converter introduced a propagation delay that became significant at 40MHz. The Espressif design is for SPI RAM clock to be further delayed vs FLASH clock, and we think that made things worse. As I said, we gave up that approach, but it seemed that the issue was when switching between SPI RAM and FLASH.

Yes it seems like an oversight because it's just a matter of paperwork to file for IC using fcc test results so I suggest you push your sales rep to get it resolved based on your EAU.

Also there are cs setup time configuration registers.

You can try the ALBWROVER32 module from Analoglamb.
The module looks like a WROOM but with PSRAM integrated and also the flash size can be custom up to 16MB.
https://www.analoglamb.com/product/alb3 ... 2mb-psram

But be careful, that currently those module are with Rev0 silicon of ESP32, not Rev1.
Since you need a larger volume, I suggest you contact them with your request, and see if they can make you Rev1 versions.
I'm also sure they have the certifications as well, so contacting them would help you.

Vader[BEN]

Vader_Mester wrote: I'm also sure they have the certifications as well, so contacting them would help you.

I don't think so, what is the ID?

Hi Tyler,

Tyler@FB wrote: I am needing the Industry Canada Certificate. The WROOM has it, but the WROVER doesn't; which is surprising. My EAU would be upwards of 5000+ pieces.

I am told that WROVER modules with Industry Canada Certification will be available soon. Depending on your timeline, you should be able to prototype with WROVER now and have the correct certifications in place before you go to production.

Who is your vendor right now? Feel free to PM me with details.

Angus

ESP_Angus wrote:Hi Tyler,

I am told that WROVER modules with Industry Canada Certification will be available soon. Depending on your timeline, you should be able to prototype with WROVER now and have the correct certifications in place before you go to production.

Who is your vendor right now? Feel free to PM me with details.

Angus

Hi Angus,

I tried to PM you, but apparently I do not have enough posts to use that feature. Would I be able to reply if you were to PM me first?

Thanks!