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Employing low power methods for the Pro Mini only makes a small difference.
It would be an excellent idea to figure out what is consuming all that current.
Can someone explain why "&len" is used in "CAN.readMsgBuf(&len, buf);"?

I am using the github CANBUS library for the seed studio (v2) CAN shield:

I know that "&" is a C++ pointer but I cannot wrap my head around why it is being used in this context.

void loop()
    unsigned char len = 0;
    unsigned char buf[8];

    if(CAN_MSGAVAIL == CAN.checkReceive())            // check if data coming
        CAN.readMsgBuf(&len, buf);    // read data,  len: data length, buf: data buf

        unsigned long canId = CAN.getCanId();
        Serial.print("Get data from ID: 0x");
        Serial.println(canId, HEX);

        for(int i = 0; i<len; i++)    // print the data
            Serial.print(buf, HEX);
Project Guidance / Re: robot
Last post by trialape - Today at 01:40 am
thats what i want to know is't possible to do it without a sensor for exemple making the eobot go for a periode of time then turn
Project Guidance / Re: robot
Last post by jremington - Today at 01:39 am
then after 700 cm
How will the robot measure that distance?
It should be sufficient to use the hardware serial port to receive MIDI and send MIDI.  Your sketch would receive the MIDI messages, recognize which byte is the velocity byte, and output the same message with the velocity adjusted.

If you want to get fancy you can use a potentiometer on an analog input pin to adjust the velocity limit on-the-fly.

I think the Arduino Pro Micro would be the best solution.  It has built-in USB (for upload and debug) PLUS a spare hardware serial port (for MIDI).  The Arduino Pro Mini is small but only has connectors for one hardware serial port.  You need a separate USB-to-Serial board or cable to do uploading and you have to use the same port for MIDI so you can't easily get serial debug output.  The Arduino Nano has an on-board USB-to-Serial adapter so you don't need an external one but that adapter uses the only hardware serial port so, again,  you have to use the same port for MIDI so you can't easily get serial debug output. 
Sensors / ADXL355 I2C Trouble
Last post by stealth_elitist - Today at 01:36 am
I am working on a project and I am trying to read the x-data from the accelerometer over I2C. Based off of the evaluation board datasheet for EVAL-357 (EVAL-355), my wiring is as follows:

P1-1 = 3V3
P1-2 = nothing
P1-3 = 3V3
P1-4 = nothing
P1-5 = ground
P1-6 = nothing
P2-1 = nothing
P2-2 = SCL
P2-3 = nothing
P2-4 = ground
P2-5 = ground
P2-6 = SDA

I am not getting a reading onto the serial monitor, and it is probably because I am accessing the device register incorrectly or my wiring is incorrect. Please help.

Code: [Select]

#include <Wire.h>
#define ADXL (0x1D)
int xdata = 0x0A;
double value = 0;

void setup() {
  Wire.begin(); //initiate the accelerometer
  Serial.begin(9600);  //initiate the serial monitor

void loop() {
  Wire.beginTransmission(ADXL); //prepare the device to read
  //ask for XDATA
  Wire.requestFrom(ADXL, 1); //request 1 byte from the device
  value =;
  Serial.println ("Value x is:");
  Serial.println(value);  //this will have to be interpreted
  delay(1000); //pause for a second
Project Guidance / Re: robot
Last post by trialape - Today at 01:30 am
so it's a line follower he follows the black line but in the end of the line the black line turns to the white color and theres two walls and the robot has to go between them then after 700 cm he has to turn right with a 90 degree angle
Looking at all the Ebay pictures, I can see one 7815 regulator and one 7915 regulator. So, a 30 volt center tap transformer will give the correct input. But the more common 24 VAC center tapped transformer will also work. The 15 volt is peak to peak.

Project Guidance / Re: Adding interrupt to shift ...
Last post by Pdiep1289 - Today at 01:25 am
Would be nice if I have any prior knowledge at all to any type of coding. But in honesty I dont. Beside what I got now I'm not planning on being a master coder, I just need to get this one project done and that's it. Not planning on revisiting the whole coding industry im a body man/painter and fabricator and just need this for a project vehicle but honestly if it's that complicated I'll figure it out.
Project Guidance / Re: robot
Last post by jremington - Today at 01:24 am
What sort of robot?
Can it go in a straight line?
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