ESP32 Forum

Hi,
I am designing a project with esp32 DOWD bare chip, followed custom design. I have to interface external memory chip via SPI protocol.
I have two questions :
1.Does ESP32-DOWD comes with Arduino Bootloader support or I will have to take some preliminary steps to get the bootloader inside the chip?
2.I have used a custom memory IC MX25U1635EM1I-10G with the ESP32 on the SPI interface. Do I have to write an interface code for memory mapping and burn it inside ESP32-DOWD first? Or I just press the upload button from my Arduino IDE with ESP32 Board support selected and everything will be configured automatically?

faizi968 wrote: ↑

Fri May 08, 2020 11:33 am

I am designing a project with esp32 DOWD bare chip, followed custom design. I have to interface external memory chip via SPI protocol.

Do I understand correctly that this is the primary flash chip for the ESP32 (ie connected to the main SPI flash pins, not a secondary SPI bus)? Will answer assuming this is the case.

Your schematic between the flash chip and the ESP32 chip should look similar to the schematic shown in the ESP32-WROOM datasheet, which is available for download from the Espressif website.

faizi968 wrote: ↑

Fri May 08, 2020 11:33 am

1.Does ESP32-DOWD comes with Arduino Bootloader support or I will have to take some preliminary steps to get the bootloader inside the chip?

ESP32-D0 has no internal program storage at all, software is loaded from the attached SPI flash chip.

There is an internal ROM bootloader inside the ESP32 which can be used to program the flash chip via UART. Please consult ESP32 datasheet section 1.4 "Strapping Pins" - you will need to reset the ESP32 with the strapping pins set for "Download Boot" as shown. Then you can use a UART interface to program the flash via Arduino or another program.

If you don't wish to do this, you'll need to copy the firmware binaries (including a software bootloader) to the flash chip via another method.

faizi968 wrote: ↑

Fri May 08, 2020 11:33 am

2.I have used a custom memory IC MX25U1635EM1I-10G with the ESP32 on the SPI interface. Do I have to write an interface code for memory mapping and burn it inside ESP32-DOWD first? Or I just press the upload button from my Arduino IDE with ESP32 Board support selected and everything will be configured automatically?

The ESP32 ROM code also has support to load firmware from the flash chip and boot from it. It will do this if the strapping pins are set for "SPI Boot" (also shown in the Strapping Pins section of the datasheet.)

However, I'm not aware of anyone using ESP32 with the flash chip model you mention. It may work, or it may not - not all SPI NOR Flash chips are exactly the same. Suggest configuring for DIO or DOUT mode to begin with, and see if these work - if you're using Arduino then you can find this under the tools menu.