I got a Humble Pi prototyping board and build a 10-channels logic level converter using this schematic:
The level converter is connected directly to all communication pins: SPI, I2C, UART and a few other GPIOs.
Everything seems to be working well (I tested the channels with a multimeter and it is working, as well as I tested the I2C using a MPC23008 working at 5V) .
However when I try to use my nRF24L01+ connecting it on the 3.3V side (the 5V side I'm going to use to programme some AVRs later on) I can communicate with it, but the data is getting corrupted and the nRF24L01+ receives the wrong settings...
When I remove the Humble Pi with the level converter and connect my nRF24L01+ directly to the GPIOs it works perfectly.
What might be the problem? Is it because the SPI pins now have a 10K pull-up resistor?
What kind of tests can I do to figure out the problem?
I'm using an Raspberry Pi Model A bought from CPC Farnell less than one month ago with Raspbian.