External flash on wrover SPI2/3 (example "ext_flash_fatfs") : no signals on SPI-output-pins

[timm_f]

Hello,

I want to connect an external SPI-flash to SPI2 or SPI3 of wrover-module (not SPI1 as it's used for on-chip ext_ram/ext_flash).
The example "ext_flash_fatfs" exactly covers this scenario.

It starts up successfully (spi_bus_initialize() and spi_bus_add_flash_device() succeed).
But fails at reading the chip_id through SPI in esp_flash_init():

Code: Select all

Failed to initialize external Flash: ESP_ERR_INVALID_RESPONSE (0x108)

I disconnected the external flash.
Oscilloscoping the SPI signals, I can't see any movement on clk / cs / mosi.
I have tried different io-pins in spi_bus_config_t, with the same result - no signals.

Using "standard" spi access (spi_bus_add_device() instead of spi_bus_add_flash_device()), I can see output signals on the oscilloscope.

Can it be a problem with the wrover module I am using (instead of wroom w/o ext. ram)?

Thanks in advance for any ideas on where to look at.

BR Timm