nRF52840 I2C large buffer write issue with SSD1306

[jerryneedell]

I ran into this issue trying to use an I2C OLED Featherwing on a nRF52840 baord -- tried on both particle_argon and pca10056 -- same result
adafruit/Adafruit_CircuitPython_SSD1306#15
Some commands like .invert() do work so it appears that the I2C interface is able to communicate with the OLED.
The same board with the same library work normally on a metro_m4_espress so this appears to be an issue with the nRF5284 I2C.

I have used other I2C devices on the nRF52840 without issues.

An SPI OLED display works normally on the nRF52840 ( tested on the pca10056)

[ladyada]

hiya to add more detail, we're almost positive it is a failure in writing 1KB+ of I2C data at once. the displays have 1 or 2 KB that we push out in one call

[jerryneedell]

It looks like the nrf I2C sends data in 16 byte chunks -- set by https://github.com/adafruit/nrfx/blob/b96950abf27229c2a3b1719d60691321246bfc94/mdk/nrf52840_peripherals.h#L205 -- it's not clear to me if this can be adjusted or if its a limitation of the HW.. I suppose I can try...

[hathach]

@jerryneedell 16 is bit size, which means 65KB each transaction. I just pushed PR to fix this #1431