Hello,
I'm using the sabertooth 2x25 motor driver in MODE 2 (RC, differential, exponential).
Sabertooth 2X25 V2 regenerative dual motor driver (also has a manual/PDF file link).
In this mode (2, RC), there are 2 signal inputs to the motor driver: S1 & S2. S1 is the PWM signal for foward/reverse for both of my drive motors. S2 is the PWM signal for steering left/right.
This is where switch 4 is set to mixed mode ON (differential drive), where you control the movements with 1 stick (2 channels) on the transmitter.
I had a tough time finding some reference code that doesn't use the S1 & S2 signal inputs for each drive motor. Example: S1 controls left motor & S2 controls right motor (independent drive).
I also like the way the author of this blog/code is not using pulseIn commands and using interrupt service routines, etc... He actually goes into detail about this.
*Btw, I'm still learning a lot, but still suck at progr./C++ as you may know, but I plan on taking an online class/tutorial to hopefully take me up another level.
He included a <PinChangeInt.h> library which I downloaded and installed.
Here is the page:
I have my receiver hooked up to the Input pins, but in the serial monitor the only thing that shows up is 'multiChannels' which I see in the code.
I would like to add some Serial.print(); Serial.println(); to give me readouts of my 2 channels (throttle & steering).
Just unsure of what variable to use (unThrottleIn..?)
Here is the code:
// MultiChannels
//
// rcarduino.blogspot.com
//
// A simple approach for reading three RC Channels using pin change interrupts
//
// See related posts -
// http://rcarduino.blogspot.co.uk/2012/01/how-to-read-rc-receiver-with.html
// http://rcarduino.blogspot.co.uk/2012/03/need-more-interrupts-to-read-more.html
// http://rcarduino.blogspot.co.uk/2012/01/can-i-control-more-than-x-servos-with.html
//
// rcarduino.blogspot.com
//
// include the pinchangeint library - see the links in the related topics section above for details
#include <PinChangeInt.h>
#include <Servo.h>
// Assign your channel in pins
#define THROTTLE_IN_PIN 5
#define STEERING_IN_PIN 6
#define AUX_IN_PIN 7
// Assign your channel out pins
#define THROTTLE_OUT_PIN 8
#define STEERING_OUT_PIN 9
#define AUX_OUT_PIN 10
// Servo objects generate the signals expected by Electronic Speed Controllers and Servos
// We will use the objects to output the signals we read in
// this example code provides a straight pass through of the signal with no custom processing
Servo servoThrottle;
Servo servoSteering;
Servo servoAux;
// These bit flags are set in bUpdateFlagsShared to indicate which
// channels have new signals
#define THROTTLE_FLAG 1
#define STEERING_FLAG 2
#define AUX_FLAG 4
// holds the update flags defined above
volatile uint8_t bUpdateFlagsShared;
// shared variables are updated by the ISR and read by loop.
// In loop we immediatley take local copies so that the ISR can keep ownership of the
// shared ones. To access these in loop
// we first turn interrupts off with noInterrupts
// we take a copy to use in loop and the turn interrupts back on
// as quickly as possible, this ensures that we are always able to receive new signals
volatile uint16_t unThrottleInShared;
volatile uint16_t unSteeringInShared;
volatile uint16_t unAuxInShared;
// These are used to record the rising edge of a pulse in the calcInput functions
// They do not need to be volatile as they are only used in the ISR. If we wanted
// to refer to these in loop and the ISR then they would need to be declared volatile
uint32_t ulThrottleStart;
uint32_t ulSteeringStart;
uint32_t ulAuxStart;
void setup()
{
Serial.begin(9600);
Serial.println("multiChannels");
// attach servo objects, these will generate the correct
// pulses for driving Electronic speed controllers, servos or other devices
// designed to interface directly with RC Receivers
servoThrottle.attach(THROTTLE_OUT_PIN);
servoSteering.attach(STEERING_OUT_PIN);
servoAux.attach(AUX_OUT_PIN);
// using the PinChangeInt library, attach the interrupts
// used to read the channels
PCintPort::attachInterrupt(THROTTLE_IN_PIN, calcThrottle,CHANGE);
PCintPort::attachInterrupt(STEERING_IN_PIN, calcSteering,CHANGE);
PCintPort::attachInterrupt(AUX_IN_PIN, calcAux,CHANGE);
}
void loop()
{
// create local variables to hold a local copies of the channel inputs
// these are declared static so that thier values will be retained
// between calls to loop.
static uint16_t unThrottleIn;
static uint16_t unSteeringIn;
static uint16_t unAuxIn;
// local copy of update flags
static uint8_t bUpdateFlags;
// check shared update flags to see if any channels have a new signal
if(bUpdateFlagsShared)
{
noInterrupts(); // turn interrupts off quickly while we take local copies of the shared variables
// take a local copy of which channels were updated in case we need to use this in the rest of loop
bUpdateFlags = bUpdateFlagsShared;
// in the current code, the shared values are always populated
// so we could copy them without testing the flags
// however in the future this could change, so lets
// only copy when the flags tell us we can.
if(bUpdateFlags & THROTTLE_FLAG)
{
unThrottleIn = unThrottleInShared;
}
if(bUpdateFlags & STEERING_FLAG)
{
unSteeringIn = unSteeringInShared;
}
if(bUpdateFlags & AUX_FLAG)
{
unAuxIn = unAuxInShared;
}
// clear shared copy of updated flags as we have already taken the updates
// we still have a local copy if we need to use it in bUpdateFlags
bUpdateFlagsShared = 0;
interrupts(); // we have local copies of the inputs, so now we can turn interrupts back on
// as soon as interrupts are back on, we can no longer use the shared copies, the interrupt
// service routines own these and could update them at any time. During the update, the
// shared copies may contain junk. Luckily we have our local copies to work with :-)
}
// do any processing from here onwards
// only use the local values unAuxIn, unThrottleIn and unSteeringIn, the shared
// variables unAuxInShared, unThrottleInShared, unSteeringInShared are always owned by
// the interrupt routines and should not be used in loop
// the following code provides simple pass through
// this is a good initial test, the Arduino will pass through
// receiver input as if the Arduino is not there.
// This should be used to confirm the circuit and power
// before attempting any custom processing in a project.
// we are checking to see if the channel value has changed, this is indicated
// by the flags. For the simple pass through we don't really need this check,
// but for a more complex project where a new signal requires significant processing
// this allows us to only calculate new values when we have new inputs, rather than
// on every cycle.
if(bUpdateFlags & THROTTLE_FLAG)
{
if(servoThrottle.readMicroseconds() != unThrottleIn)
{
servoThrottle.writeMicroseconds(unThrottleIn);
}
}
if(bUpdateFlags & STEERING_FLAG)
{
if(servoSteering.readMicroseconds() != unSteeringIn)
{
servoSteering.writeMicroseconds(unSteeringIn);
}
}
if(bUpdateFlags & AUX_FLAG)
{
if(servoAux.readMicroseconds() != unAuxIn)
{
servoAux.writeMicroseconds(unAuxIn);
}
}
bUpdateFlags = 0;
}
// simple interrupt service routine
void calcThrottle()
{
// if the pin is high, its a rising edge of the signal pulse, so lets record its value
if(digitalRead(THROTTLE_IN_PIN) == HIGH)
{
ulThrottleStart = micros();
}
else
{
// else it must be a falling edge, so lets get the time and subtract the time of the rising edge
// this gives use the time between the rising and falling edges i.e. the pulse duration.
unThrottleInShared = (uint16_t)(micros() - ulThrottleStart);
// use set the throttle flag to indicate that a new throttle signal has been received
bUpdateFlagsShared |= THROTTLE_FLAG;
}
}
void calcSteering()
{
if(digitalRead(STEERING_IN_PIN) == HIGH)
{
ulSteeringStart = micros();
}
else
{
unSteeringInShared = (uint16_t)(micros() - ulSteeringStart);
bUpdateFlagsShared |= STEERING_FLAG;
}
}
void calcAux()
{
if(digitalRead(AUX_IN_PIN) == HIGH)
{
ulAuxStart = micros();
}
else
{
unAuxInShared = (uint16_t)(micros() - ulAuxStart);
bUpdateFlagsShared |= AUX_FLAG;
}
}
