I use DAC board AD9739A-FMC-EBZ (Rev. C) with Virtex 7 FPGA board. AD9739A connected to VC707 board no directly, but via intermediate board. The problem of this project in control lines for AD9739A. During PCB desing of intermediate board, wires of SPI interface was not connected. Instead this, was connected two wires of I2C interface: SCL, SDA. This lines not connected to DAC chip, it's connected to PIC controller PIC18F24J50-I/ML. PIC controller can programming DAC chip AD9739A via SPI lines on AD9739A-FMC-EBZ board. Commands for programming of DAC controller get from PC via USB cable.
Can I use PIC controller via I2C data lines for retranslate commands to DAC? Have this PIC controller mode like "echo" when it will retranslate commands from I2C input pins to SPI out pins and resend answers from DAC chip back?
I see another solution of this problem - reprogram PIC controller with other selfmade program, which will retranslate data from I2C to SPI and back. But in this case PIC controller will lost ability to cowork with PC via USB. This will undesirable. Anybody can help me with some solution?