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adafruit / Adafruit_nRF52_Arduino

Adafruit code for the Nordic nRF52 BLE SoC on Arduino
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SPIM3 requires VBUS to work #773

Closed amowry closed 1 year ago

amowry commented 1 year ago

Operating System

Windows 11

IDE version

2.1.0

Board

ItsyBitsy NRF52840 Express

BSP version

release

Sketch

Any SPI sketch

What happened ?

SPI doesn't work if VBUS is not present at startup. It is the same as this SPIM3 bug in the CircuitPython version, but I thought I'd mention it here because I'd like to know if there is a workaround or fix for the Arduino environment: https://github.com/adafruit/circuitpython/issues/5233

Also discussed here: https://forums.adafruit.com/viewtopic.php?t=188798&start=15

And here: https://devzone.nordicsemi.com/f/nordic-q-a/83266/spim3-not-work-standalone/350598

How to reproduce ?

Use SPI without VBUS present (e.g. with battery power) MOSI never fires.

Debug Log

No response

Screenshots

No response

dhalbert commented 1 year ago

We have been unable to get a response from Noridc about this problem. It appears to be a hardware issue, or an undocumented issue with the Nordic driver that should handle this case. As you see, there has been no response in the Nordic DevZone about this. SPIM3 has had hardware issues. You might raise the issue yourself in DevZone, perhaps opening a new issue. An Arduino example might get further than our CircuitPython observations, though they may want an nRF SDK or nrfx example.

amowry commented 1 year ago

Thanks for the info and quick response! I can force it to use SPIM2 instead of SPIM 3 by changing this in SPI.cpp:

// default to 0 #ifndef SPI_32MHZ_INTERFACE #define SPI_32MHZ_INTERFACE 0 #endif

To this:

// default to 0 #ifndef SPI_32MHZ_INTERFACE #define SPI_32MHZ_INTERFACE 1 #endif

If there's a way to implement that in an Arduino sketch, that would be simpler.

dhalbert commented 1 year ago

I think you could just put

#define SPI_32MHZ_INTERFACE 1

in your sketch, because it's #ifndef'd in the code above, and not defined otherwise for the ItsyBitsy. (For the Feather nRF52840, both SPI and SPI1 are defined.)

amowry commented 1 year ago

Thanks-- I did try that, both before and after including SPI.h, but it didn't seem to have an effect. Not sure why (?).

hathach commented 1 year ago

it is probably that 32Mhz SPI need hfclk() which is enabled by USB when detect VBUS, you can try to enable hfclk() to see if that works.

amowry commented 1 year ago

Thanks! I'd rather not use the hfclk so I'll stay with the previously mentioned fix, but I appreciate the suggestion.

hathach commented 1 year ago

should be closed now, highspeed 32Mhz needs hfclk to work