Search found 22 matches

by Albert
Thu Sep 10, 2020 9:31 am
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Re: Unpredictable PWM behaviour when powered via 5v pin

i figured that the pwm will work okay if the chip is powered using a specific usb cable(Anker). i tried many other usb cables but all did not work. They will all supply about 5.01v but when the chip is connected, the voltage output at the 5v regulator reduces to about 4.68v. With the Anker cable, th...
by Albert
Tue Sep 08, 2020 9:16 am
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Re: Unpredictable PWM behaviour when powered via 5v pin

or could it be that the usb chip converter has to be powered in a specific way with the data pins connected in a certain way?
by Albert
Tue Sep 08, 2020 7:30 am
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Re: Unpredictable PWM behaviour when powered via 5v pin

i meant laptop and not pc. the motor driver works well when it is connected to anything that has got a battery as the power supply
by Albert
Tue Sep 08, 2020 6:54 am
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Re: Unpredictable PWM behaviour when powered via 5v pin

Tom, The motor driver/controller works with anything between 0 and 5v. As long as the nodemcu is powered using something that has a battery(powerbank/pc), it works well. The problem comes when battery supply to the nodemcu is eliminated. i dont understand this at all. Is there something that a batte...
by Albert
Mon Sep 07, 2020 5:56 pm
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Re: Unpredictable PWM behaviour when powered via 5v pin

Tom, the pwm_1, dir_1,pwm_2,dir_2 pins are all set as outputs. When i disconnect power to the motor driver, there's no change in the voltage at the pwm outputs. in fact what has shocked me today is that when i test the circuit again, the pwm output voltage is now the same(1.92v) whether using powerb...
by Albert
Mon Sep 07, 2020 7:07 am
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Re: Unpredictable PWM behaviour when powered via 5v pin

sorry i dont have a scope to see where it rises when disconnecting. im using the mdd10a motor driver and not able to attach datasheet here.
by Albert
Sun Sep 06, 2020 7:24 pm
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Re: Unpredictable PWM behaviour when powered via 5v pin

I added 0.1uf bypass caps on both the input and output but there's no change. The voltage measured on the 5v pin remains constant(4.56v) even when the problem occurs. ive found out that the pwm output when powered using pc or powerbank is 2.56v but when powered from the lm7805 regulator, the pwm out...
by Albert
Sun Sep 06, 2020 6:57 am
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Re: Unpredictable PWM behaviour when powered via 5v pin

No i don't have the bypass caps. could this be the cause?
by Albert
Sat Sep 05, 2020 7:13 pm
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Re: Unpredictable PWM behaviour when powered via 5v pin

Yes all my grounds are connected together. Im using LM7805 regulator for my 5v supply with a current capacity of 1.5A.
by Albert
Wed Aug 26, 2020 1:31 pm
Forum: General Discussion
Topic: Unpredictable PWM behaviour when powered via 5v pin
Replies: 18
Views: 775

Unpredictable PWM behaviour when powered via 5v pin

I have a NodeMCU breakout board which im using as a wifi access point to control dc motors, through a motor driver, using the pwm pins 32 and 33 at a pwm frequency of 1800Hz on pwm channels 4 and 5 respectively. im using a pwm resolution of 8 bits to write a pwm value of 150 on each of the pins at d...

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