Michael Shimniok / TinyCHR6dm

TinyCHR6dm is a simplified interface for the CH Robotics CHR-6dm AHRS

Dependents:   AVC_20110423

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TinyCHR6dm Class Reference
Public Member Functions

TinyCHR6dm Class Reference

TinyCHR6dm is a simplified interface for the CH Robotics CHR-6dm AHRS http://www.chrobotics.com/index.php?main_page=product_info&cPath=1&products_id=2. More...

#include <TinyCHR6dm.h>

Public Member Functions

 TinyCHR6dm ()
 Creates an protocol parser for CHR-6dm device.
void parse (char c)
 Parse a character of data from CHR-6dm.
float readYaw (void)
 Get the current yaw (course)
bool dataReady (void)
 Determine if yaw data is ready.
void resetReady (void)
 Reset the data ready flag.
void send_packet (Serial *serial, uint8 pt, uint8 n, char data[])
 Create a packet using specified PT, N, and data and adding 'snp' header and 2-byte checksum.
int status (void)
 Return latest status packet type sent by the AHRS, resets statusReady() to false.
bool statusReady (void)
 Indicates whether a status message is ready to be read with status()
char * statusString (int status)
 Converts status to readable text string.

Detailed Description

TinyCHR6dm is a simplified interface for the CH Robotics CHR-6dm AHRS http://www.chrobotics.com/index.php?main_page=product_info&cPath=1&products_id=2.

Written by Michael Shimniok http://www.bot-thoughts.com/

In the style of TinyGPS, this library parses a subset of the CHR-6dm packets to provide a minimal set of data and status messages to the caller. Also provides utility to send commands to the AHRS. This is an early release and a work in progress, so the interface may change significantly over the next couple of versions. Also, the current version only supports reading yaw data. More may be supported in the future. 

 #include "mbed.h"
 #include "TinyCHR6dm.h"

 Serial pc(USBTX, USBRX);
 Serial ahrs(p26, p25);
 TinyCHR6dm ahrsParser;
 DigitalOut myled(LED1);
 Timer t;

 void recv() {
   while (ahrs.readable())
      ahrsParser.parse(ahrs.getc());
 }

 int main() {
   char data[128];
   int status;
           
   t.reset();
   t.start();
   pc.baud(115200);
   ahrs.baud(115200);
   ahrs.attach(recv, Serial::RxIrq);


   wait(0.5);

   // Configure AHRS
   data[0] = Accel_EN;
   ahrsParser.send_packet(&ahrs, SET_EKF_CONFIG, 1, data);
   wait(0.5);
   status = ahrsParser.status();
   pc.printf("Status: %02x %s\n", status, ahrsParser.statusString(status));
   
   ahrsParser.send_packet(&ahrs, ZERO_RATE_GYROS, 0, 0);
   wait(0.5);
   status = ahrsParser.status();
   pc.printf("Status: %02x %s\n", status, ahrsParser.statusString(status));

   ahrsParser.send_packet(&ahrs, EKF_RESET, 0, 0);
   wait(0.5);
   status = ahrsParser.status();
   pc.printf("Status: %02x %s\n", status, ahrsParser.statusString(status));

   while(1) {
     int millis = t.read_ms();
     if ((millis % 500) == 0) {
       while (!ahrsParser.dataReady());
       pc.printf("yaw: %.2f\n", ahrsParser.readYaw());
     }
   }
 }

Definition at line 166 of file TinyCHR6dm.h.

Constructor & Destructor Documentation

TinyCHR6dm (  )

Creates an protocol parser for CHR-6dm device.

Definition at line 20 of file TinyCHR6dm.cpp.

Member Function Documentation

bool dataReady ( void   )

Determine if yaw data is ready.

Parameters:
returntrue right after parsing SENSOR_DATA from AHRS

Definition at line 80 of file TinyCHR6dm.cpp.

void parse ( char  c )

Parse a character of data from CHR-6dm.

Parameters:
cis the character to be parsed

Definition at line 26 of file TinyCHR6dm.cpp.

float readYaw ( void   )

Get the current yaw (course)

Returns:
the current inertia-frame yaw aka course

Definition at line 76 of file TinyCHR6dm.cpp.

void resetReady ( void   )

Reset the data ready flag.

Definition at line 84 of file TinyCHR6dm.cpp.

void send_packet ( Serial *  serial,
uint8  pt,
uint8  n,
char  data[] 
)

Create a packet using specified PT, N, and data and adding 'snp' header and 2-byte checksum.

Checksum Datasheet: After the CHR6-dm receives a full acket, it checks to ensure that the checksum given in the last two bytes matches the sum of all preceding bytes in the packet.

Definition at line 90 of file TinyCHR6dm.cpp.

int status ( void   )

Return latest status packet type sent by the AHRS, resets statusReady() to false.

Parameters:
returnsthe status as an integer corresponding to the TX packet type

Definition at line 126 of file TinyCHR6dm.cpp.

bool statusReady ( void   )

Indicates whether a status message is ready to be read with status()

Parameters:
returnstrue if a status message has been received since the last call to status()

Definition at line 131 of file TinyCHR6dm.cpp.

char * statusString ( int  status )

Converts status to readable text string.

Parameters:
returnspointer to static string containing status message text

Definition at line 135 of file TinyCHR6dm.cpp.

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