Is the SPI flash module's CS pin exposed on ESP-12E module?

[liudr]

I am wondering if any one the GPIO pins on the ESP-12E module is the CS pin for the flash, such as GPIO11 (CS0). I'm interested in using SD card with the module and wonder if I can use any GPIO pins as CS. Thanks.

[Roberthh]

You can use any GPIO pin as CS. There is a SD card adapter board from Wemos, which cost about 1 $ and works nice.

[liudr]

You can use any GPIO pin as CS. There is a SD card adapter board from Wemos, which cost about 1 $ and works nice.

So any pin exposed can be used as CS? I'm just making sure I'm not accidentally using the CS for the internal flash and mass up a module.

[Roberthh]

Any GPIO which is not used otherwise. The ESP-12E seems to expose CS of the internal flash on the small edge, labeleld CS. So do not use that one.

[liudr]

Any GPIO which is not used otherwise. The ESP-12E seems to expose CS of the internal flash on the small edge, labeleld CS. So do not use that one.

Thanks again! So the small edge has the SPI pins. If I make my own board, the I should use GPIO 6,7, and 8 as SPI bus wires and another GPIO other than 11 as CS, correct?

[Roberthh]

Use GPIO13 for MOSI, GPIO12 for MISO, GPIO14 for CLK and GPIO 2, 4 or 5 for CS. Since GPIO4 and 5 are typically used for I2C, you may choose GPIO2. GPIO2 is also used for boot control, so it must not be pulled low during boot. But using it as an output isOK.

[deshipu]

You can't use pins 6-11, as they are used internally for the flash memory chip.

[liudr]

Thanks guys. I am a circuit board designer. I'm trying to wrap my head around the new MCU. All these help a lot.

[liudr]

So the SPI_xx markings on this pin out diagram are for internal FLASH and the HSPI_xx markings are for interfacing with SPI devices such as sd cards? If that's the case, I understand why using "GPIO13 for MOSI, GPIO12 for MISO, GPIO14 for CLK and GPIO 2, 4 or 5 for CS."

[deshipu]

It's actually traditional to use gpio 15 for cs, as it's what used for cs when it's handled in hardware (of course, in our case we handle it ourselves, so you can use any pin, but since gpio 15 is already marked as cs...).