Hello,

I am starting with a new project, where the FX3 is connected to a FPGA. The main data flow is from the FPGA to USB. So I have to transfer data from, P-Port to U-Port and may be vice versa. The Synchronous Slave FIFO example should be a good base for this.

I also have to communicate from USB-Side with the FX3 ARM-Processor. I think I can do this by adding two additional DMA-Channels from USB (2 additional Bulk Endpoints / Sockets) to the CPU (CY_U3P_CPU_SOCKET_CONS and CY_U3P_CPU_SOCKET_PROD). I have tested this already with the FX3 Development-Board and it seems to work.

But what is the best way for a communication between the FX3 CPU and the FPGA?

Should I add two DMA-channels from P-Port to the CPU, like I have done this already for the U-Port.? Can I use the “sync_slave_fifo_2bit” interface to address 4 threads (sockets) where 2 are connected with the U-Port (AUTO-Channel In/Out) and 2 are connected with the CPU (MANUAL-Channel-In and MANUAL-Channel-Out)?

Another way for the communication may be the mailbox registers. But I have found no example for them.

I know I can also use the I2C-Bus to communicate with the FPGA, but a communication via the P-Port should be much faster.

Hi,

you may also be able to use the UART (max. baudrate 4MHz) to communicate between FPGA and FX3, that is a bit faster than the I2C (max 1MHz). Third solution but may be the best if you also like to communicate to FPGA while transferring data from P-port to USB3.

regards,

lumpi

The UART is not an option for me, because the first revision of my board is already out at the manufacturer. I have connected all GPIF II Pins and the I2C-Bus to the FPGA. However I have not connected the UART Pins, because I want to use the UART for debug purposes only. Nevertheless thank you for your suggestion.

Ok then it is too late for that. But take care, because you can not use the UART api in DMA mode (not sure if also in other mode) while you are in some interrupt/callback context (e. g. GPIO interrupt). In this cases it is better you are using an own created SPI with GPIO switching, that will work all the time. The SPI could easy be converted through a hardware SPI to UART bridge.

regards

lumpi

Hi Diwo,

I think the purpose of I2C bus in your design is to send/recieve control/status information between FX3 and FPGA.

As per my understanding, the frequency of  information running on this path is less. So, I think I2C bus should be good enough as you already designed your hardware boards.

Thanks,

sai krishna.

I think I will start with I2C-Interface.

However I am having all possibilities with the GPIF II Interface, because I have connected all signals to the FPGA. I think my configuration (FX3 connected to FPGA) is very common.

That's why I hoped someone has a solution for a communication besides the I2C-Bus or the UART.