First: how did you get those pin numbers on rephone breakout? Use this please to address pins: seeedstudio.com/wiki/Xadow_GSM_Breakout
So it would be like
Display – RePhone breakout
MOSI – E2
SCLK – C1
CS – ?
RST – ?
DC – ?
But from this image seeedstudio.com/wiki/images/ … ons-04.jpg
your connections seems very wrong:
Display – RePhone breakout
MOSI – Digital 4: SPI_SCK
SCLK – Digital 2: CTP_SDA
CS – Digital 14: MICBIAS
RST – Digital 13: ACCDET
DC – Digital 15: AU_VIN1_N
Also, the datasheet says
“Vdd = 2.4V to 3.5V” - you should check if the display works with power supply as low as 2.8V. If yes, throw out the level converters, so one less thing to care about and one less thing that can mess up things.
And to the CS pin: can you please try the display with your uno, with CS pin fixed to GND? I am curious now, because the datasheet is not exact about it. As far as I know, it must work with CS fix pulled to GND.
So my guess is
- maybe wrong connected pins
- level converter messing things up (the uno uses 5V, you run on 3.3V, so 1.7V diff, but 2.8-3.3V has only 0.5V difference, so maybe it can’t drive the transistors correctly)