3 Replies Latest reply on Jan 17, 2017 3:38 AM by nishanta_46

    AN84868 UART no output



      I have a CYUSB3KIT-003, and I can see the UART output following the user guide.


      But, when I try the AN84868 img file, there is not any UART output.


      Is any missing operation?



        • 1. Re: AN84868 UART no output



          As per the Table 7 of FX3 Datasheet, FX3 has two sets of UART Interface. One is on GPIOs 53 to 56. Other is on GPIOs 46 to 49.


          Here the GPIOs 53 to 56 are shared by both SPI and UART Interfaces. When SPI is disabled in your firmware (i.e useSpi = CyFalse is set in CyU3PDeviceConfigureIOMatrix API), this interface acts as UART Interface by default. When both SPI and UART are enabled in your firmware (useSpi = CyTrue, useUart = CyTrue), then GPIOs 53 to 56 act as SPI and GPIOs 46 to 49 act as UART.


          In the CYUSB3KIT-003, the GPIOs 53 to 56 are connected to our UART to USB Bridge for Debugging. When running many examples in which SPI is disabled, you can notice UART logs using this.


          But the AN84868 firmware has SPI Interace enabled while configuring the FPGA (check in cyfxconfigfpga.c file). So, at this time, Pins 46 to 49 act as UART, So you will not be able to notice the logs. Once FPGA is configured, the CyU3PDeviceConfigureIOMatrix is called again (in cyfxslfifosync.c file), this time with SPI Disabled. So from then on you will be able to see the UART logs.


          Note: If you want to view logs from pins 46 to 49 also, you will have to connect these pins on the board to an external UART to USB bridge and view logs from that device.




          - Madhu Sudhan

          • 2. Re: AN84868 UART no output

            Hi Madhu,


            Thanks for your explanation.


            I encounter another problem, when I download AN84868 img file to EEPROM, it is fail.


            But I download USBBulkSourceSinkLED.img to EEPROM, it is success.


            I use Control Center and it is same download operation for these two img files.


            Is any restrictions for AN84868?





            • 3. Re: AN84868 UART no output

              There is no such restriction. You should be able to program the EEPROM with this firmware. Please check the I2C bus traffic using a I2C analyzer. Is it happening all the time you program or does it fail only sometime. It may happen that the EEPROM may not be ready when you selected to download.