Hi,everybody!
I use nRF52832,supply volt 3.0V normal,program can be downloaded , run and debug,i ensure the program is accurately.To control a gpio P0.09,on the hardware, P0.09 series a resistor to the led and the led is grounded,in the program I set P0.09 to high level.The led doesn't light up after the program is downloaded,but the bluetooth program normal works.Why? TKS.
Standard output, 0.5mA, taking a look at the spec for that LED it wants more like 20mA, at 0.5mA you're barely turning it on. Even if you could source 20mA from the pin you have a 1K resistor (where did you get THATvalue from). Assuming a Vf on the LED of 2.0v and a supply of 3.0V, your drop over the resistor is 1.0v so your current would be limited to about 1mA even if the pin could supply more. 1mA is so low on the graph of luminous intensity vs current as to be basically .. off.
You can't drive a 20mA nominal current LED from a GPIO, even in High mode (~5mA) and certainly not in standard mode (0.5mA) and even if it could supply 20mA, your current limiting resistor is way too large. I calculate 50 ohms to be closer to the mark.
Thank you for your reply.
I tested it today,even short-circuited the resistance,there's still no reaction.I measured the gpio high level output voltage only about 0.18v,low level output voltage about 0.00...V. I guess the gpio has no output at all.Don't know why?Is it possible that the chip is broken?
Yes,I read all your messages.This means that the drive capacity is not enough, but I have short-circuited the series resistance between LED and GPIO,Is it not enough to connect the led directly to the gpio port?
This is basic electronics. If the drive is limited to 0.5mA then that is all the current you can get out of the pin which means it will drop the voltage however low it needs to be to get 0.5mA. So without the resistor you get the max current available which is 0.5mA and that's probably a voltage across the LED of about 0.2v, hard to say really as that is so far away from the operating region the charts don't really cover it.
You can't drive an LED from a GPIO like that.
I also changed to 50omhs, and the test lights were not on.
and at this time, the working voltage of MCU was adjusted to 3.0v
I've now explained this to you three times. I will do it a fourth. You cannot light an LED of that type that with 0.5mA. 50 ohms would be appropriate for a GPIO at 3v which could source 20mA, but this can't source 20mA, it can source 0.5mA.
You have two problems
1) you are trying to drive something with 20mA from a 0.5mA source
2) even if you weren't whatever calculation you did for your original resistance was entirely wrong.
However in this case 2) doesn't matter because of 1)
I've now explained this to you three times. I will do it a fourth. You cannot light an LED of that type that with 0.5mA. 50 ohms would be appropriate for a GPIO at 3v which could source 20mA, but this can't source 20mA, it can source 0.5mA.
You have two problems
1) you are trying to drive something with 20mA from a 0.5mA source
2) even if you weren't whatever calculation you did for your original resistance was entirely wrong.
However in this case 2) doesn't matter because of 1)
ok,tks,I'll add a MOS to increase its drive capacity.
Hi RK,
Before testing again, I removed the LED and the resistance,As you say,I set all P0.09 and P0.10 as output high level, and no external devices were connected at this time. These two pins were suspended. At this time, the output voltage of these two pins should be 3.0v (at this time, the operating voltage of MCU is 3.0v), but after my measurement, it was found that the output voltage of these two pins was around 0.2v or below 0.2v.There is no high level voltage of about 3.0v output at all
Hi,RK
Just now, I suspended the other IO port, wrote the program to enable the IO port to work normally, which can be raised and pulled down.
And I set the usable gpio to toggle the high and low level once every 1 second. Then I used the multimeter to see that the gpio is 3.0v for a while and 0v for a while.See the led lights up every once in a while and off every once in a while.
The above is my description of the phenomenon after the experiment.
Although you don't reply, but I also want to say with you, the things settled, is not what we discussed yesterday, is a question of NFC, P0.09 and P0.10 was just what I used as a gpio, it is the default NFC function, so I need to set the register to normal gpio, then everything is normal work, also do not need to add the MOS tube, just change the NFC function to gpio function, can work normally, but still want to thank you.
const uint32_t UICR_ADDR_0x20C __attribute__((at(0x1000120C))) __attribute__((used)) = 0xFFFFFFFE;
