This simple code fragment crashes and restarts MCU!

[CuriousOne]

Also it will crash randomly even when GPS is connected. Here's how output looks:

Time: 15:41:00
Time: 15:41:01
Time: 15:41:02
Time: 15:41:03
Time: 15:41:04
Time: 15:41:05
Time: 15:41:06
Time: 15:41:07
Start ok <------- it crashed and restarted here
Time: 15:41:10
Time: 15:41:11
Time: 15:41:12
Time: 15:41:13
Time: 15:41:14

So I think this is issue with arrays?

[HenrikOlsson]

Could be, easy to verify

    ' Wait for data from GPS
    serin2 GPS_RX,85,[gps_char] 'If I remove this line or disconnect the GPS, MCU will crash!
    ' Store data in buffer
    gps_data[i] = gps_char
    i = i + 1

   If i >= 80  'or whatever size you set the array to
     serout2 portc.5,84, ["Next char will overrun buffer"]
   ENDIF

[amgen]

not sure but first use of i and i+1 might overrun.

[Jerson]

I am not currentl with PBP, so, please refer the manual where necessary.

It is most likely you are overrunning the specified receive buffer gps_data of 80 bytes as you are not doing any bounds checking to keep the data within that 80 bytes region. That is trashing the variables declared beyond the 80 bytes boundary.

Ideally, you should receive characters until a terminating character is received like a CR or a $00 character (whichever method is used by the module) or the buffer limit is reached (i = 80 as per your code)

edit:looks like I posted together with Henrik and amgen.

[CuriousOne]

Yes you're correct, i is overrun.
This is AI generated code, by the way

I added this:

    if i>=80 then
    serout2 portc.5,84, ["Oops!", 10, 13]
    i=0
    endif

And now output looks like this with GPS connected:
Oops!
Oops!
Oops!
Time: 16:36:37
Time: 16:36:38
Time: 16:36:39
Time: 16:36:40
Oops!
Time: 16:36:42
Oops!

And only "Oops!" with GPS disconnected, but there are no more resets...

[Jerson]

If you're gettings false data when GPS is disconnected, perhaps you have left the RX pin floating. Maybe you could see if adding a pull-up resistor eliminates that problem for you.