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Forum Index : Microcontroller and PC projects : Unintended GPIO output during start of program
| Author | Message | ||||
| Arne Regular Member  Joined: 05/01/2025 Location: GermanyPosts: 48 |
Is there an easy possibility to block the output of data to the GPIOs before/during setting of GPIOs as outputs. My code is as follows: SetPin 24,dout SetPin 25,dout SetPin 26,dout SetPin 27,dout SetPin 29,dout SetPin 31,dout SetPin 32,dout SetPin 34,dout SetPin 11,dout SetPin 12,dout SetPin 14,dout SetPin 15,dout SetPin 16,dout SetPin 17,dout SetPin 19,dout SetPin 20,dout Port(11,2,14,4,19,2,24,4,29,1,31,2,34,1)=&B1111111111111111 If I start the program for approx. 5ms (during the SetPin - phase) unintended outputs to the GPIOs happen. A flickering of < 1 ms would be ok. Any ideas ? Arne |
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| matherp Guru  Joined: 11/12/2012 Location: United KingdomPosts: 10965 |
The pins will be high-Z when the program starts. If important you would need pullup or pulldown resistors on your board |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 3016 |
> pin(1)=1 :setpin 1,dout :? pin(1):pin(2)=1 :setpin 2,dout :? pin(2) 1 1 > So you could try:- Pin(24)=1 : SetPin 24,dout Pin(25)=1 : SetPin 25,dout Pin(26)=1 : SetPin 26,dout Pin(27)=1 : SetPin 27,dout Pin(29)=1 : SetPin 29,dout Pin(31)=1 : SetPin 31,dout Pin(32)=1 : SetPin 32,dout Pin(34)=1 : SetPin 34,dout Pin(11)=1 : SetPin 11,dout Pin(12)=1 : SetPin 12,dout Pin(14)=1 : SetPin 14,dout Pin(15)=1 : SetPin 15,dout Pin(16)=1 : SetPin 16,dout Pin(17)=1 : SetPin 17,dout Pin(19)=1 : SetPin 19,dout Pin(20)=1 : SetPin 20,dout Port(11,2,14,4,19,2,24,4,29,1,31,2,34,1)=&B1111111111111111 It should make them go straight from high-Z to 1 without first being set to 0 (the default after Setpin) before the port command. Edited 2026-01-18 21:33 by phil99 |
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| Arne Regular Member Joined: 05/01/2025 Location: GermanyPosts: 48 |
To set the pins before SetPin command worked perfect. Thanks all, Arne |
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| DaveJacko Regular Member Joined: 25/07/2019 Location: United KingdomPosts: 96 |
While we're on the subject of GPIO.. can anyone point out what stupid mistake I'm making here? wire together GP0 and GP1 setpin GP0,dout setpin GP1,din pin (GP0)=1 print pin(GP1) - prints a 0 !! also tried pin(GP0)=0, and PWM 1Khz 50% checked with a meter, volts/freq as expected. Just getting 0 on GP1 (I'm ultimately trying to get a settick type interrupt > 1 KHz ) Thanks in anticipation mates. Try swapping 2 and 3 over |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 3016 |
> setpin GP0,dout : setpin GP1,din > pin(GP0)=1 : ? pin(GP1) 1 > Check with a meter that you are getting 3.3V on GP1 at the pad on the Pico module. If so you may have a dead pin. Try GP2 etc. |
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| DaveJacko Regular Member Joined: 25/07/2019 Location: United KingdomPosts: 96 |
Thanks, Phil, I've tried that bit of code verbatim right now.. mine returns a zero yes, I previously checked with meter, 3+ volts tried another pico zero, same. I think I may be making an even more fundamentally stupid mistake, I'll sleep on it with a glass of Aussie red, will let you know how I get on Try swapping 2 and 3 over |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4244 |
You have a space after pin in pin (GP0)=1 Please try it without the space (sorry, I'm guessing it matters here but may be wrong). John |
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| DaveJacko Regular Member Joined: 25/07/2019 Location: United KingdomPosts: 96 |
thanks, John, but well spotted! tried it, don't think that's the problem.. sleeping on it Try swapping 2 and 3 over |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 3016 |
I would have expected that to be the issue too, had I noticed it. A CODE window makes spaces clearer. However :- > pin(GP0)=0 : ? pin(GP1) Did not expect that! 0 > pin (GP0)=1 : ? pin(GP1) '1 space 1 > pin (GP0)=0 : ? pin(GP1) '1 space 0 > pin (GP0)=1 : ? pin(GP1) '2 spaces 1 > |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6455 |
It should work as presented. As Phil suggested, try GP2 etc To see if one of the pins is reserved for some system purpose, try new option list list pins Jim VK7JH MMedit |
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| mozzie Senior Member  Joined: 15/06/2020 Location: AustraliaPosts: 204 |
G'day DaveJacko, It might be a good idea to post the version of PicoMite and options list you are using, it could be a problem with a specific variant or option rather than generic. I have tried your code on a RP2350A and RP2040 using V6.02.00RC7 and both work as expected, something strange going on somewhere.  What happens if you apply 3v3 direct to GP1? Regards, Lyle EDIT: Also tested on RP2040-Zero with V6.02.00RC7 and it works as expected. Possibly an option setting conflict? Edited 2026-01-19 12:45 by mozzie |
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| DaveJacko Regular Member Joined: 25/07/2019 Location: United KingdomPosts: 96 |
I went back in my shed to experiment further.. (objective; simply to link two pins, one with a pwm output >1000 Hz, the other to trigger an interrupt, >1000 Hz) using gp0 as PWM out and gp1 as interrupt in, just returns constant gp1=0 other way round, gp0 as int and gp1 as pwm produces interrupts as expected! Just to experiment further, tried random pins GP10,GP11 linked together, GP10 won't drive GP11, and GP11 won't drive GP10, just get pin()=0 despite meter showing 0v/3v3 levels, at 1 Hz in case you were wondering on RP2040 Pico Zero running V6.00 aaargh!.. surely something that's my fault  Try swapping 2 and 3 over |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 3016 |
Jim made an important suggestion earlier. If that doesn't reveal anything save the contents of A: and the current program then apply Clear_flash.uf2. That should restore it to Factory Fresh. Then when you install new firmware it won't be compromised by the remains of the previous one. |
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| DaveJacko Regular Member Joined: 25/07/2019 Location: United KingdomPosts: 96 |
I'm putting my perceived GPIO problem on the back-burner for now (I'll try the clear_flash.uf2 nuke in due course, thanks Phil and all for your help) I'm sure it will ultimately be my fault. Having read the excellent manual carefully, using a hardware int to give a steady clock is unlikely to work, hardware ints are only serviced after completion of commands, so can be missed. Thought of a new approach. I forgot that 'TIMER' counts in microseconds, (assumed milliSecs) so something like this might give a steady loop time mainloop: timer=0 <do your stuff> waitloop: if timer<0.1 then goto waitloop 'ie 10 kHz goto mainloop That said, the new stepper commands for RP2350 really are marvellous ! Try swapping 2 and 3 over |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8568 |
If it's of any use, the Count input has a hardware interrupt rather than being software dependent. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| DaveJacko Regular Member Joined: 25/07/2019 Location: United KingdomPosts: 96 |
Thanks Mick, I'll try that with a count of 1  Try swapping 2 and 3 over |
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