5 Replies Latest reply on Apr 1, 2020 10:27 AM by BiBi_1928986

    Programming at 2.5v made it work. Why?

    MaLo_1836446

      Hello all,

       

      Im using the miniprog4 programming a CY8C4248-L485 on a PCB i made with it partially populated. All hand soldered so briding is a possibility.

       

      I just got my 4th board to program after ditching my first three which now i will go back to. I am curious as to why i had to make the Miniprog4 power at 2.5v for it to work. It seemed to short out at 5v and was able to detect the chip at 3.3v, but when i hit program it gave me the FF FF 13 A0 error. but at 2.5 v it worked just fine.

       

      Also do i need a .1uf cap from xres to ground or a pull up resistor? The data sheet has a XRES DC Characteristic section and says Rpullup is about 5kohms, does this mean I need to install a 5kohm resistor or it has one internally?

       

      Thanks for everyones time.

        • 1. Re: Programming at 2.5v made it work. Why?
          GaneshD_41

          Hi

           

          Please compare your board schematic with our development board schematic. If possible can you please attach the schematic of your custom board?

           

          https://www.cypress.com/documentation/development-kitsboards/cy8ckit-046-psoc-4-l-series-pioneer-kit

           

          >>"Also do I need a .1uf cap from xres to ground or a pull up resistor? The data sheet has a XRES DC Characteristic section and says Rpullup is about 5kohms, does this mean I need to install a 5kohm resistor or it has one internally?"

           

          --> The pull up resistance is internally present. so, there is no need for any external pull up resistor. The decoupling capacitor is optional.

           

          Thanks and regards

          Ganesh

          • 2. Re: Programming at 2.5v made it work. Why?
            MaLo_1836446

            I wont be able to post a schematic for a while.

             

            When troubleshooting i started with just the MCU and the 5 pin header for the Miniprog4, i had two .1uf caps, one on power and one on the xres. When I connected it it came up under 3.3v and the miniprog4 shutdown when i set it to 5v. I added the other 5 or 6 .1uf and one 1.0uf caps for the rest of the power pins and it no longer came up. So i removed all the caps except for one .1 uf and repeated the above errors. I know without posting the schematic there is not much help you can provide. But i guess what would cause a higher voltage to malfunction?

            • 3. Re: Programming at 2.5v made it work. Why?
              BiBi_1928986

              My guess..., the pcb has shorted Vccd to Vddd.  With this connection, the device should only be operated at 1.8V.  As you observed, it worked at 2.5V, but that was just luck.

               

              Vccd should only be connected to a single 1uF capacitor for this PSoC.  There should be no other connections to the Vccd pin.

               

              Let us know what you discover.

              • 4. Re: Programming at 2.5v made it work. Why?
                MaLo_1836446

                I went to work to check the schematic and you guessed it. I shorted VCCD to the rest of the power pins out of error. Luckily the cap for Xres and Vccd are next to each other and I can just cut the trace from cap to cap to sever its connection to the other pins and bypass it to ground at the same time. Thank you for your help,

                • 5. Re: Programming at 2.5v made it work. Why?
                  BiBi_1928986

                  Hello.

                  Good to hear you found the fault and were able to modify the pcb.

                   

                  BTW, the installed PSoC chip may not be reliable since 5V was previously applied to it.  The PSoC internal 1.8V regulator does not generally survive after 5V has been applied to Vccd pin.  So, don't be too surprised if you find the chip fails in the future and you need to replace it.

                   

                  Good luck with your project.