We are trying to build an RC interface to transform a PPM signal from the RC (remote control) into a PWM signal for motor controls. The idea is to build a 2-channel robot that goes forward % back, right & left.
Right now we face the issue that the that we intend to use PIC16F628A to generate this signal, but this chip only has 1 CCP port. As I understand it, the CCP pin is how the PIC detects external interrupts.
So how do I implement the 2 interrupts needed? Do I grab another PIC or is there any way I can use some other pins to handle the required interrupts?
Any help much appreciated
EDIT for clarification: PPM - pulse-position modulation:
The remote control will send a signal that has it's information stored in the duration of the uptime of the pulse. If there are no inputs, the receiver will transmit a pulse of 1.5ms. This will correspond to an output PWM of 0%, the motors that will receive this PWM will not be moving.
If the duration of the PPM pulse is 2ms, this means that the control is moving forward or to the right (depending on the channel being used), and 1ms if the control is moving back or to the left (again depending on the channel)
Currently we are using the PIC in capture mode, as soon as the rising edge of the pulse is detected, we start the timer, which is then only stopped once it detects the falling edge.
This will give us the information we need to send the PWM signal. 2ms means 100%, 1ms means -100%, and 1.5ms means 0% (motors off). An H-bridge will be used to correct the direction of the PWM for the negative values, but this has already been implemented.
We are using this PIC because it's what we have at our school, and some other teams have used it before and it has more references. If there exists another PIC that better does what we intend, please let me know as well, but I'm not sure that is necessary.