ESP32 Flash SPI Speed Issues

autodog
Posts: 9
Joined: Sat Sep 21, 2019 5:41 am

ESP32 Flash SPI Speed Issues

Postby autodog » Sat Sep 21, 2019 5:50 am

Hey everyone,

I have an ESP32-WROVER-B on multiple custom PCBs with an issue I can't explain:

- If I set the menuconfig -> Serial flasher config -> Flash SPI speed to 26, 40, or 80MHz I can flash an image successfully but I will receive a checksum error when the device reboots
- If I set the menuconfig -> Serial flasher config -> Flash SPI speed to 20MHz everything seems to run OK

Is this SPI flash speed expected? If not, any ideas what might cause my issues?

Thanks!
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ESP_Sprite
Posts: 9719
Joined: Thu Nov 26, 2015 4:08 am

Re: ESP32 Flash SPI Speed Issues

Postby ESP_Sprite » Mon Sep 23, 2019 4:16 am

What does the custom PCB look like? Do you have anything connected to the flash pins that may affect operation?

WiFive
Posts: 3529
Joined: Tue Dec 01, 2015 7:35 am

Re: ESP32 Flash SPI Speed Issues

Postby WiFive » Mon Sep 23, 2019 4:28 am

Also make sure you are not pulling up gpio12 or have set the vdd_sdio efuse to 3.3v

autodog
Posts: 9
Joined: Sat Sep 21, 2019 5:41 am

[solved[ Re: ESP32 Flash SPI Speed Issues

Postby autodog » Tue Sep 24, 2019 1:30 am

ESP_Sprite:

You're right on the money: I had an I2C device hanging off of GPIO21 and 22 which also happen to be used by SPI flash on the ESP32-WROVER. This was causing my SPI Flash to be very flaky.

Removing my device from those two GPIOs cleared everything up.

Thanks for the pro-tip!
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WiFive
Posts: 3529
Joined: Tue Dec 01, 2015 7:35 am

Re: ESP32 Flash SPI Speed Issues

Postby WiFive » Tue Sep 24, 2019 2:45 am

Do you mean pad 21&22 aka gpio 7&8?

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