spi problem with p12 pin and boot modes

[anthony_soben]

Hi,
I try to work with an ADC converter in SPI. I have connected the device like this:
SCK - > p10
MOSI - > p11
MISO -> p12
But i have a problem because the MISO is in wait at high level and after a reset the wipy enters a safe boot mode (the orange led blink).

Which solutions can I have to avoid this problem?

[Andreas Bruring]

@charly86
and while there at it they can also mention that p8 must not be pulled up when you want to flash the firmware. because if you don't it wont get into download_boot mode but instead into HSPI_FLASH_BOOT mode and will start a reset loop. we also had that problem.

[Charly86]

I faced the same issue with a custom board mapped I2C to P12, and spend long time to find out there was a safe boot mode preventing some of my boards to start.
I think the pinout mapping should mention a warning on this pin (not only text below as today) because other warning pin have a warning signal but not this one) P2 GPIO0 too but has I'm coming from ESP8266 I was aware about this one ;-)

Something like that should help other doing the same mistake as us !!!

[Andreas Bruring]

then why may i ask is that the default pin for the SPI MISO. i am having the same problem with a prototype.

according to to spi specs the slaves are supposed to be high impedance. but apparently some pull up somewhat.

is there a workaround possible with a high resistance pull-down resistor?

[livius]

@anthony_soben
choose different pin
e.g. change pins in init

spi = SPI(0, mode=SPI.MASTER, baudrate=2000000, polarity=0, phase=0, pins=('P19','P20','P21'))