Needed additional pins for PSRAM

q2222ch
Posts: 20
Joined: Mon Feb 27, 2017 8:30 pm

Re: Needed additional pins for PSRAM

Postby q2222ch » Fri Jun 02, 2017 12:26 pm

@ESP_igrr:
With the two mentioned points (pin strapping/ eFuse Deep-Sleep problems) I mean based on the information in the Espressif documentation and the posts in the forum:
a.) Pin strapping: That the LDO of the ESP is configured with a VDD_SDIO = 3.3V till the eFuses are read (even if they are correctly programmed for 1.8V) when something with the external pull-up pin strapping at the MTDI pin goes wrong because the internal default is "pull-down" = 3.3V. This way round you can destroy an external 1.8V pSRAM.

b.) Deep-Sleep: You can benefit from the disabling of the VDD_SDIO disabling in Deep-Sleep via software. If you try to avoid a.) with an own external 1.8V supply for VDD_SDIO you have to find an own solution to disable the external supplied 1.8V VDD_SDIO in Deep-Sleep and reenable it on time when the ESP32 should leave Deep-Sleep to bring Iq down.

ESP_igrr
Posts: 2067
Joined: Tue Dec 01, 2015 8:37 am

Re: Needed additional pins for PSRAM

Postby ESP_igrr » Fri Jun 02, 2017 1:05 pm

Ah, okay, "If you try to avoid a.) with an own external 1.8V supply" was the part I didn't get from your previous post.

No, we're not suggesting to use an external supply. Setting the strapping pin to the correct level for the D2WD should be sufficient. Documentation will be updated to explain this point.

q2222ch
Posts: 20
Joined: Mon Feb 27, 2017 8:30 pm

Re: Needed additional pins for PSRAM

Postby q2222ch » Sat Jun 03, 2017 11:04 pm

I tried to create a little overview how to connect the external pSRAM to the ESP32-D0WD and ESP32-D2WD chips based on the information in the forum and the different documents. Based on the information that I could find there are still "two pins" missing (in the case of the ESP32-D2WD). Could somebody from Espressif provide the missing entries, please (the fields with the red question marks)?
ESP32_pSRAM.png
ESP32_pSRAM.png (292.73 KiB) Viewed 5034 times

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