Customer:
I’m using GPIO pins 12 and 33 on a Raspberry Pi 3 to control servo motors. The output signal amplitude on these pins is 3.3V, so I purchased two logic level converter modules to step the signal up to 5V for the motors. The motors will be powered from a separate supply where I’ll use a step-down module to reduce 12V to 6V. I’m unsure how to connect the logic level converter modules and have attached a schematic I’d like help with.
Original message (Croatian)
na Raspberry Pi 3 koristim fizičke pinove 12 i 33 za kontrolu servo motora. Amplituda impulsa na njihovim izlazima je 3.3V pa sam u Vašoj trgovini kupio dva logic level konventer modula kako bih na motore slao signal od 5V. Motori se napajaju s posebnog napajanja čiji ću izlaz od 12V smanjiti na 6V pomoću step down modula. Nisam siguran kako trebam spojiti logic level konventer module. U privitku je shema pa bih Vas zamolio da mi je u Paintu dovršite.
Attachment omitted in migration: shema2.bmp
Originally submitted via email support on 19 September 2017. Migrated to the forum for community visibility.
Soldered Support:
Consider the B side as the Raspberry Pi side and the A side as the servo motor side.
Connect BVCC to 3.3V from the Raspberry Pi.
Connect AVCC to the voltage you want to convert the signal to (6V in your case).
Connect BGND and AGND together to the grounds from both the Raspberry Pi and the external power supply, so all grounds are common.
Bring one PWM signal from the Raspberry Pi to BSCL, and you’ll get that signal at 6V amplitude on ASCL, which you then connect to the first servo.
The same applies to BSDA → ASDA for the second servo signal.
Original message (Croatian)
dakle recimo da je B strana(svaka oznaka ima A ili B, npr. Agnd i Bgnd) Raspberry Pi, dok je A strana strana servo motora.
Na BVCC spajate 3.3V s raspberryja
na AVCC spajate napon na kojega želite pretvoriti signal servo motora(6V u Vašem slučaju)
BGND i AGND spajate zajedno i na grounde od Raspberryja i eskternog napajanja – tako da su svi groundi zajedno
sada na BSCL dovodite jedan PWM signal s Raspberry Pi-ja, a na ASCL ćete dobiti taj signal s 6V amplitudom kojega onda spajate na servo
isto vrijedi i s BSDA → ASDA
Zovnite ako trebate još pomoći
Customer:
So I can bring the second PWM signal from the Raspberry Pi to BSDA and get it on ASDA to drive the second servo. This means I don’t need a second logic level converter module—one module is enough for both signals?
In my schematic I labeled them servo1 and servo2, but actually each of these is a pair of servo motors where one in each pair has reversed rotation direction. I purchased four step-down modules (one for each servo motor), but I’m wondering if I can use one step-down module for two servo motors in a pair, since I’m concerned that even a small difference in output voltage between different step-down modules could cause a speed difference between paired servos.
One more confirmation: should I place a 1000 µF capacitor as close as possible to the servo motor, and place the largest capacitor I can on the 12V power supply output?
Original message (Croatian)
dakle drugi PWM signal s Raspberry Pi-ja mogu dovesti na BSDA i s ASDA ga odvesti na drugi servo pa prema tome ne trebam koristiti drugi logic level modul, tj. dovoljan mi je jedan logic level modul za oba signala?
U shemi sam nacrtao servo1 i servo2, ali u biti servo1 su dva servo motora gdje je kod jednog obrnut smjer rotacije (poveznica ), isto vrijedi i za servo2. Kupio sam četiri step-down modula (za svaki servo motor po jedan), ali zanima me mogu li koristiti jedan step-down modul za dva servo motora koji idu u paru jer se bojim da bi čak i mala promjena u izlaznom naponu različitih step-down modula izazvala razliku u brzini rotacije servo motora koji idu u paru.
Još da potvrdim, fizički što bliže servo motoru staviti kondenzator od 1000 uF, i na 12V izlaz od napajanja staviti kondenzator što većeg kapaciteta?
Puno hvala na susretljivosti!
Soldered Support:
Yes, one module is enough for both signals.
You can use one step-down module for two servo motors.
Correct about the capacitors!
Original message (Croatian)
Da, tako je - jedna pločica je dovoljna za oba signala.
Možete koristiti jedan step-down za dva servo motora.
Točno za kondezatore!
Javite jel radi 