I have an old RC car but without the transmitter so I built my own Rx/Tx using MCU and 2.4Ghz transceiver, however, I want to use the car's original H-Bridge but not sure if I understood how that circuit works.
Here is the schematic for the bridge:
My understanding is that P1 and P2 are for forward direction and provide different speeds!?, while P3 is the reverse direction. Correct me if I am wrong.
My questions are:
1- Can I use logic level to drive P1-3 (directly from MCU pin) ?
2- When setting one of them high should the other two be low? Can P1 and P2 be high at the same time?
3- What is the purpose of R1?, Why only 1Ω?, Why 10W? and Why it is only connected to Q1 and Q2 and not T9 (since all three are PNP high side transistors)
4- Why does it have a diode D4 for only one of the inputs (P1)?
5- What is the purpose of D1, D2 and D3?
6- How does T1 drive T5 and Q2? Since its collector and emitter are connected to the base of the other transistors! no ground or vcc!? I am confused.
7- Can I use PWM to control the speed of this bridge? (default frequency for Atmel Atmega328 is 32K)
(Note: C1, C2 and C3 are actually polarized electrolytic capacitors)
----- Updates ------
Here is the modified design after fixing the swapped transistors pins, removing the slow forward circuit and adding flyback diodes:
So how does it look? anything that need to be changed? removed? added?