Michael,

The mDot has a “hard” serial port available in addition to the USB debug port. Here’s a link to the pinout:

https://developer.mbed.org/platforms/MTS-mDot-F411/#pinout-diagram

You should be able to create a mbed Serial object with those two pins to communicate with your GPS module.

Hope this helps!

Cheers,

Mike

Michael,

Pins PA_9 & PA_10 are the USB debug interface. The other available UART is on pins PA_2/SERIAL_TX & PA_3/SERIAL_RX. Are you using PA_2 & PA_3? If not, please try those, e.g.

Serial gps(SERIAL_TX, SERIAL_RX);

The default baud rate of mbed Serial objects is 9600. You can change it with the Serial::baud() function.

Cheers,

Mike

Michael,

Two things:

1) I don’t think 4800 baud is supported. I suggest using 9600 or faster.

2) Is SerialGPS a class you’ve defined? If you use a standard Serial object instead, does that work?

Cheers,

Mike

Have you tried:

Serial gps(PA_2, PA_3);

The TX pin should be first.

Also you could see if any debug comes out at the mbed default 9600 if there are issues before the application is loaded.

The app won’t start, there should be debug message

“pinmap not found for peripheral”

Hi,


#include "TinyGPS.h"

This worked fine for me, I used the TinyGPS for NMEA parsing.

I am also trying to integrate GPS module to mDot. Yet, GPS module needs 3V to 3.6V. How can it be sourced from mDot?

I am sourcing the mDot with 3.7V single cell LiPo battery, it is a bit higher for GPS module.

VOUT pin provides 3V @ 25mA which is not sufficient for GPS, it must be cabaple of at least 40 mA.

Any suggestions?

I am observing a debug output problem with SerialGPS. However I think I have narrowed it down to a combination of presence of mDot.h and SerialGPS.h – still NOT able to figure out the place of conflict but I have two starter programs – both of them do NOT interface to the LoRa radio. Both of them have code included for the Grove GPS – and I am using hte SerialGPS library. On the program that does NOT include the mDot.h – the program works fine and I am able to print the values of the GPS. However on the other program where I am setting up the mDot as well with mDot.h included in the program – the Serial output goes for a toss or locks up.

Any idea on what may be going on?

Mike,

I am glad you asked that question because yes there is another difference – I have mbed-rtos as well along with mDot. I had to include it because mDot needs rtos.h.

So this is another difference between the two code bases…

Ashu

The short version of what happens is that at the beginning of the program before I go in a loop to read the BME280 sensor – I print out to the console the config values of mDot. This printing is erratic – sometimes it prints only 20% of the config, sometimes it gets stuck on the first line, sometimes it makes it almost to the first sensor output BUT it basically freezes – that is no more console output.

I suspect though that the system is up because I have the LED blink at the beginning and I can see the LED still blinking.

Including the header file of course does not do anything – its only when I declare the pins:

SerialGPS gps(PA_2, PA_3);

Ashu,

Can you post your source code?

-Mike

Ashu,

I took a look at the code you posted and nothing jumped out at me. However, you mentioned that you didn’t include the GPS processing code which is presumably where the issue is. If you post the entire application, I’ll try to take a look at it.

Moving in a slightly different direction, MultiTech also has a mDot product called the MTDOT-BOX which might suit your needs.

http://www.multitech.com/brands/multiconnect-mdot-box

The MTDOT-BOX has onboard sensors, GPS, and an LCD screen in addition to the mDot module. We have an example application that uses all of these sensors and does LoRa communication as well.

Cheers,

Mike

I have been able to parse nmea sentences using a TinyGPS+ port ( very similar to TinyGPS – same author) by using bufferedSerial to buffer the NMEA strings so that TinyGPS can parse them in the main loop

I have these imports :

#include "TinyGPSplus.h" // can also use TinyGPS
#include "BufferedSerial.h"

then I create these :

TinyGPSPlus gps;
BufferedSerial uartGPS(XBEE_DOUT, XBEE_DIN,1024); // tx, rx,buffer size //

in main ( before the usual “while(1)” loop: ( “Setup()” in ArduinoLand
I set up the baudrate of the GPS interface :

// set up UART to recieve GPS strings
    logInfo("setting up GPS serial port");
    uartGPS.baud(9600);

and then in the While(1) loop ( or if you are From ArduinoLand (loop() )

// parse all the data in the serial buffer
        while(uartGPS.readable()>0) {
           // gps << uartGPS.getc();
            gps.encode((char)uartGPS.getc());
        }

you can then read the GPS parameters off exacly like the TinyGPS / TinyGPS+ libraries show , ie.
int altitudeGps = gps.altitude.meters();

• This reply was modified 8 years, 3 months ago by daniel de kock.