I am working on a Maple r5, and I am powering it up through a USB. When I connect an LED diode to the Vcc port of the Maple, the LED starts flashing, I don’t think this is normal. And when I set an I/O port to OUTPUT, and write 1 to it, it starts flashing too.
How can I get a stable output from my Maple?
Vcc is oscillating
(8 posts) (4 voices)-
Namir Jawdat
MemberPosted 4 years ago # -
siy
MemberThe Maple on-board regulator is quite weak and can source not so much power to external consumers. Maple r5 docs explain this in more details: http://leaflabs.com/docs/hardware/maple.html#power-regulation-on-the-maple
Posted 4 years ago # -
Namir Jawdat
MemberSiy, Thanks for your reply.
I am powering the Maple through USB which means I am using 5V, and I am connecting an LED in series with a 10K Ohm resistor to the Vcc, which leads to less than 0.5m Amp current usage by an external circuit. And I notice that the LED is flashing ON/OFF instead of being stable ON.Posted 4 years ago # -
gbulmer
ModeratorNamir Jawdat -
I can think of a few possible causes for the behaviour you are seeing. It is possible that there is a short somewhere.How fast does the LED flash? The flashing might be caused by the thing supplying USB power, or the regulators on the board. It is possibly the STM32F itself, but I doubt that for now.
How many jumpers have you got in the power header?
There should be only one plugged in bridging two pins (in the correct direction). For simplicity, remove all the others.Have you got any external voltage source? Remove that.
Have you got anything plugged into the LiPo socket? remove that.
Remove the LED, and all the power jumpers. So there should be nothing plugged into the Maple except the USB cable.
Does the onboard power LED flash? If it does, the problem is on the board, or something the board is touching somewhere.Have you got a voltmeter or multi-meter This will present very little load so you can measure voltages.
Very carefully, avoiding making a short, measure the voltage at each of the power header pins (with all the jumpers removed) compared with ground. Only one should be showing a voltage (5V at the USB power header pin). Is this voltage steady, or is it 'flashing'?
If this voltage is 'flashing' the problem is upstream towards the USB power. If it is steady, it is downstream.
(Full disclosure: I am not a member of LeafLabs staff)
Posted 4 years ago # -
Namir Jawdat
MemberHi gbulmer,
Thanks for your reply and time.
When I remove the jumper the on-board LED doesn’t flash.
I have 1 jumper on the USB position, I don’t have any more jumpers. I did the voltage check and all the pins have 0.59V while only 1 of the USB pins has 5.03V and it is steady.
And I did couple of verifications:
I can program the on-board LED without any problem, make it ON, OF, blinking and changing the blinking speed.
The on-board LED is connected to pin 13, so I connected an 8.2K Ohm resistor in series with an LED to pin 13. When the on-board LED is OFF the external LED is OFF which is normal, when the on-board LED is ON, the external LED is flashing!!. They are connected to the same pin.
When I check the voltage on the VCC or pin 13 without load, the voltage is stable, when I put any load on the VCC or pin 13 the voltage is fluctuating.
I am new to the leaflabs Maple and will appreciate any help to solve this issue.Posted 4 years ago # -
gbulmer
ModeratorNamir - I'm glad you found it, a flashing LED was the only explanation I had based on your last post.
poslathian - are you applying the British meaning of 'blinking' :-)
If not, here is one:
http://www.rapidonline.com/Electronic-Components/5mm-Flashing-LEDs-76184Posted 4 years ago #
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