Timeline for help reconstructing blinking LED circuit that required GPIO #17 pin low rather than high
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
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| Nov 20, 2017 at 0:32 | comment | added | Richard Chambers | No the LED is not bad as once I changed the circuit it was bright as normal. I think there is still too little information to come up with an answer at this time. | |
| Nov 20, 2017 at 0:31 | comment | added | Steve Robillard | @RichardChambers More likely you have a bad led. You can confirm by making the last connection to a ground pin rather than pin 17. | |
| Nov 20, 2017 at 0:30 | comment | added | Richard Chambers | Tinkering around this afternoon I ended up with the same condition using a 200 ohm resistor though pulling power from the 3.3v rail. The LED was dim and not bright. I am wondering if there is some other resistance in the circuit when going from 3.3v power pin to GPIO #17 with a red LED and a 200 ohm resistor and then doing a LOW on GPIO #17 to turn the LED on. See the mention of pull-up and down 50K ohm resistors on GPIO pins here wiringpi.com/reference/core-functions | |
| Nov 19, 2017 at 13:09 | comment | added | Steve Robillard | @RichardChambers You might have used the 5 volt pin instead of 3.3 Volts, but that wont make a real difference here. one other option for why the LED was dim is that you used something other than a red led. | |
| Nov 19, 2017 at 13:05 | comment | added | Richard Chambers | Ok, so you surmise that I had connected the 3.3v power pin into my circuit? The LED was very dim and the resistor was a 200 ohm resistor from the Osoyoo kit. I used the same resistor when I tried it again when it operated correctly. However I am not sure if I used the same LED since I put the LED back into the plastic baggie with the others. The LED was definitely dim in the first trial. In other experiments with a standalone power supply with a similar circuit and a larger value resistor the LED was definitely dimmer. | |
| Nov 19, 2017 at 11:50 | history | answered | Steve Robillard | CC BY-SA 3.0 |