Joseph Bradshaw / Mbed 2 deprecated mbed_DFRobotJoystick_parse

Example program of decoding the DF Robotics xbee joystick serial output

Dependencies:   mbed

Weapons and Systems Engineering mbed DFRobotJoystick Interface

/media/uploads/jebradshaw/dfjoystick_xbee.jpg

This page provides an example of reading an ASCII comma separated variable string from the DR Robot Wireless Gamepad using the mbed micro-controller. The DF Robbot Wireless Gamepad is an Arduino programmable game controller with an on-board xbee wireless transceiver module. The gamepads used in the Weapons and Systems Engineering Department have been reprogrammed with the arduino sketch listed below.

/media/uploads/jebradshaw/joes_dfrobot_gamepad_example_20141021_mode.ino

The output of the joystick follows the GPS NMEA 0183 protocol as an ASCII string preceded by an "$JOYSTK", and terminated with an asterisk and a two character checksum (hex representation).

Below is a screen shot of the data streaming in TeraTerminal when the gamepad is connected directly to the PC (through a virtual COM port).

/media/uploads/jebradshaw/df_robot_data_stream.jpg

mbed_DFRobot_joystick_parse.cpp@1:bc6098f1dd1a, 2015-02-09 (annotated)

Committer:
jebradshaw
Date:
Mon Feb 09 13:42:35 2015 +0000
Revision:
1:bc6098f1dd1a
Parent:
0:ce988e55f00d 
mbed WSE TSD xbee DF Robotics Joystick parse example

Who changed what in which revision?

UserRevisionLine numberNew contents of line
jebradshaw 1:bc6098f1dd1a 1 // Example of parsing the serial string from the DF Robot Joystick with the mbed
jebradshaw 0:ce988e55f00d 2 #include "mbed.h"
jebradshaw 0:ce988e55f00d 3
jebradshaw 0:ce988e55f00d 4 DigitalOut myled(LED1);
jebradshaw 0:ce988e55f00d 5 Serial pc(USBTX, USBRX); //tx, rx via USB connection
jebradshaw 0:ce988e55f00d 6 Serial xbee(p13, p14); //tx, rx via Xbee socket
jebradshaw 0:ce988e55f00d 7
jebradshaw 0:ce988e55f00d 8 int main() {
jebradshaw 0:ce988e55f00d 9 char joystr[100]; //used to store the whole joystick string
jebradshaw 0:ce988e55f00d 10 int buttonsAll; //16bit representation of all buttons
jebradshaw 0:ce988e55f00d 11 int button[16]; //individual button states (normally high)
jebradshaw 0:ce988e55f00d 12 int js_lr_L; //Left Joystick Left/Right movement
jebradshaw 0:ce988e55f00d 13 int js_ud_L; //Left Joystick Up/Down movement
jebradshaw 0:ce988e55f00d 14 int js_lr_R; //Right Joystick Left/Right movement
jebradshaw 0:ce988e55f00d 15 int js_ud_R; //Right Joystick Up/Down movement
jebradshaw 0:ce988e55f00d 16 int chksum; //checksum for error correction
jebradshaw 0:ce988e55f00d 17
jebradshaw 0:ce988e55f00d 18 pc.baud(921600); //crank up the PC baudrate (USB) to avoid latency between data acquisition
jebradshaw 0:ce988e55f00d 19 xbee.baud(9600);
jebradshaw 0:ce988e55f00d 20
jebradshaw 0:ce988e55f00d 21 pc.printf("\r\n\r\n%s\r\n", __FILE__);
jebradshaw 0:ce988e55f00d 22
jebradshaw 1:bc6098f1dd1a 23 while(1) {
jebradshaw 0:ce988e55f00d 24 while(xbee.readable()) //clear out the remaining characters in the buffer
jebradshaw 0:ce988e55f00d 25 char c = xbee.getc();
jebradshaw 0:ce988e55f00d 26
jebradshaw 1:bc6098f1dd1a 27 //read the serial string from the xbee (starts with '$', ends with \r\n
jebradshaw 1:bc6098f1dd1a 28 xbee.scanf("$%s\r\n", &joystr);
jebradshaw 1:bc6098f1dd1a 29
jebradshaw 1:bc6098f1dd1a 30 // pc.printf("%s\r\n", joystr); //used for debugging
jebradshaw 1:bc6098f1dd1a 31
jebradshaw 1:bc6098f1dd1a 32 if(!strncmp(joystr, "JOYSTK", 6)){
jebradshaw 1:bc6098f1dd1a 33 if (sscanf(joystr, "JOYSTK,%X,%d,%d,%d,%d*%X", &buttonsAll, &js_lr_L, &js_ud_L, &js_lr_R, &js_ud_R, &chksum) >= 1) {
jebradshaw 1:bc6098f1dd1a 34
jebradshaw 1:bc6098f1dd1a 35 // iterate through buttonsAll (each bit) to assign value MSB first
jebradshaw 1:bc6098f1dd1a 36 for(int i=15;i>=0;i--){
jebradshaw 1:bc6098f1dd1a 37 if(buttonsAll & (1 << i))
jebradshaw 1:bc6098f1dd1a 38 button[i] = 1;
jebradshaw 1:bc6098f1dd1a 39 else
jebradshaw 1:bc6098f1dd1a 40 button[i] = 0;
jebradshaw 1:bc6098f1dd1a 41 pc.printf("%1d ", button[i]);
jebradshaw 1:bc6098f1dd1a 42 }
jebradshaw 1:bc6098f1dd1a 43
jebradshaw 1:bc6098f1dd1a 44 //pc.printf("%7 %5d %5d %5d %5d 0x%02X\r\n", buttonsAll, js_lr_L, js_ud_L, js_lr_R, js_ud_R, chksum);
jebradshaw 1:bc6098f1dd1a 45 pc.printf("%5d %5d %5d %5d\r\n", js_lr_L, js_ud_L, js_lr_R, js_ud_R);
jebradshaw 1:bc6098f1dd1a 46 }
jebradshaw 1:bc6098f1dd1a 47 else{
jebradshaw 1:bc6098f1dd1a 48 pc.printf("BAD parse %s\r\n", joystr);
jebradshaw 1:bc6098f1dd1a 49 }
jebradshaw 1:bc6098f1dd1a 50 }
jebradshaw 0:ce988e55f00d 51 myled = !myled; //toggle LED for activity verification
jebradshaw 0:ce988e55f00d 52 }//while(1)
jebradshaw 0:ce988e55f00d 53 }//main