Does the micro SD share interface with SPI GPIO?
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Hi colleagues, I just connected LED to SPI MISO and found that there are some activity. Led blinking.
Is my assumption (that microSD share interface with SPI) correct?Many thanks!
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@Kris-Kelvin the system's primary "disk" storage is an SPI flash under the shield can - unless you reconfigure things to run from a ramdisk or are satisfying everything from soft caching, occasional SPI activity would occur just from normal (internal) filesystem access.
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If Omega2 SPI is using MT7688 SOC's native hardware based SPI arrangement (i.e., not using software based SPI using any GPIO pins), then there is no conflict with pins used in SD card interface.
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@ccs-hello, thank you! Am I right understand that it means that I could safely use SPI MISO pin as GPIO for my needs without worrying that it has any impact on other system functionality?
And here is another questions: how to disable this activity? Id' like to use this pin as a LED indicator
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All I have stated is about there is no relationship about SD card interface pins with SPI pins.
On the other hand, the on-board Flash ROM is using the SPI pins.
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@Kris-Kelvin said in Does the micro SD share interface with SPI GPIO?:
@ccs-hello, thank you! Am I right understand that it means that I could safely use SPI MISO pin as GPIO for my needs without worrying that it has any impact on other system functionality?
Absolutely not!
You cannot use this pin for custom purpose unless you are running from a ramdisk and are confident that nothing will try to talk to the SPI flash on which booting depends. Corrupt that and your system is basically bricked - as far as anyone knows, requiring removing the shield can to fix.
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@Chris-Stratton Following the schematics (https://github.com/OnionIoT/Onion-Hardware/blob/master/Schematics/Omega.pdf) GPIO 9 8 7 6 are floating by default, while hardware SPI (B51, B50, A54, B49) connected to internal FLASH MX25L1605DM2I. So it is logical to assume that GPIO 9 8 7 6 are used for software SPI emulation, which could be utilized as microSD interface (not clear from schematics) and in the same time as external SPI (for that developers, who not using microSD, maybe). Native SPI most probably staying aside anyway.
Сould you give a link to the source that provides comprehensive information on this?
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RESET. Omega 1 or Omega 2?
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@ccs-hello Omega2+
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@Kris-Kelvin
https://github.com/OnionIoT/Onion-Hardware/blob/master/Schematics/Omega.pdf
That is the schematic of Omega (Qualcomm Atheros AR9331 SoC)Please read at least this part of the official Onion Omega2(+) (MediaTek MT7688 SoC) Documentation.
Important & Special GPIOs - SPI Pins & Onboard Flash StorageBriefly:
GPIOs 7, 8, and 9 (SPI CLK, MOSI and MISO) cannot be used as regular GPIOs.
The SPI CS1 pin, GPIO 6, may be still used as a regular GPIO when configured as a GPIO using
omega2-ctrl gpiomux set spi_cs1 gpio
See also this warning: Pins Important for Booting the Omega ie Omega2(+).BTW MISO is an input pin (SPI Flash Data_Out --> MT7688 SPI_MISO)
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@György-Farkas thank you. The only detail that still makes me doubt that the GPIO 6 should floating on boot. Obviously LED + resistor to GND will work as pull-down connection...
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The only detail that still makes me doubt that the GPIO 6 should floating on boot. Obviously LED + resistor to GND will work as pull-down connection...
No, it won't - even a red LED has a forward voltage that would easily exceed the threshold for unambiguous interpretation as a logic 0, and that of other colors can exceed 3v.
If a pin needs to be low at boot for config strapping, it needs a direct pulldown resistor, not routing through an LED.
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@Chris-Stratton thank you for the answer! I just tried with the LED on GPIO1 and it booting and working just fine.
However, my attempt of connection to FW_RST was fall to the factory reset by some reason...
maybe you have any idea?
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@Kris-Kelvin said in Does the micro SD share interface with SPI GPIO?:
my attempt of connection to FW_RST was fall to the factory reset by some reason
What does that even mean?
Try saying it again, specifically and clearly - what exactly did you do, what were you expecting, and what exactly happened?