Actions
Forum Thread Details
  • State Not Answered
  • Replies 6 replies
  • Subscribers 284 subscribers
  • Views 629 views
  • Users 0 members are here
Related
See a helpful answer?

Be sure to click 'more' and select 'suggest as answer'!

If you're the thread creator, be sure to click 'more' then 'Verify as Answer'!

MikroBus GPIO

MATRIX7878

Hello,

     I am using a ZuBoard 1CG and am trying to use the MikroBus as GPIO pins so I can program a parallel LCD screen.  I am getting strange signals coming out of the pins.  Even just alternating GPIO signals creates strange results.  There are large multi-second gaps for some lines, some have random switches and some keep running forever despite a stop condition.  From the schematic, the only IC between the SoC and MikroBus connector is a 1.8 V to 3.3 V converter.  Why would I have strange behavior?

Thank you

Parents
  • 0

    It sounds like an open connection somewhere, possibly an 'enable/disable' pin or the like. Or perhaps if your cables are too long and/or are not screened and some interference is getting onto them from some distance away.

    The power supply could be responsible - I don't remember 1.8v to 3.3v converters, but that doesn't mean there aren't any. If your supply voltage is not close enough to 1.8v then the output might not be close enough to 3.3v to drive the circuit. Can you short all the inputs to zero volts and then check to see if all the outputs are stable? Assuming that none of them are square-wave generators by default when power is applied, of course.

    I don't know the ZuBoard, but the more I think about it the more I think there is a dry joint somewhere or even an unsoldered pin. I've seen it before, a pin on a SMD in mid-air, i.e. not soldered to the PCB. Or, if it is a very old ZuBoard, there might be dendrites. I've even seen a PCB where the track layout was wrong close to an IC in such a way that pin 1 was connected to hole 16, pin 2 to pin 15, etc. The quick cure was to desolder the IC and solder it to the other side of the PCB; this was not acceptable to the quality inspectors but it proved the point. The other 99 boards were scrapped without any further work being done on them.

Reply
  • 0

    It sounds like an open connection somewhere, possibly an 'enable/disable' pin or the like. Or perhaps if your cables are too long and/or are not screened and some interference is getting onto them from some distance away.

    The power supply could be responsible - I don't remember 1.8v to 3.3v converters, but that doesn't mean there aren't any. If your supply voltage is not close enough to 1.8v then the output might not be close enough to 3.3v to drive the circuit. Can you short all the inputs to zero volts and then check to see if all the outputs are stable? Assuming that none of them are square-wave generators by default when power is applied, of course.

    I don't know the ZuBoard, but the more I think about it the more I think there is a dry joint somewhere or even an unsoldered pin. I've seen it before, a pin on a SMD in mid-air, i.e. not soldered to the PCB. Or, if it is a very old ZuBoard, there might be dendrites. I've even seen a PCB where the track layout was wrong close to an IC in such a way that pin 1 was connected to hole 16, pin 2 to pin 15, etc. The quick cure was to desolder the IC and solder it to the other side of the PCB; this was not acceptable to the quality inspectors but it proved the point. The other 99 boards were scrapped without any further work being done on them.

Children
No Data