Trying to parse nmea with double and strtod

RE: Trying to parse nmea with double and strtod

Hakon — Tue, 24 Jun 2025 12:09:20 GMT

So you get a build error when you try to build with CONFIG_FPU=y? What SDK version is that?

RE: Trying to parse nmea with double and strtod

simon884 — Mon, 23 Jun 2025 10:43:15 GMT

Yes sorry typo issue

RE: Trying to parse nmea with double and strtod

Hakon — Fri, 20 Jun 2025 11:27:28 GMT

What is CONFIG_FU? Did you mean CONFIG_FPU?

RE: Trying to parse nmea with double and strtod

simon884 — Thu, 19 Jun 2025 07:51:28 GMT

Ok thanks, just a question, if I try to enable CONFIG_FU I got an error when I'm trying to build

INVALID CONFIG: ( CONFIG_TFM_ENABLE_FP OR CONFIG_TFM_ENABLE_MVE OR
CONFIG_TFM_ENABLE_MVE_FP ) AND NOT CONFIG_TFM_ENABLE_CP10CP11

RE: Trying to parse nmea with double and strtod

Hakon — Wed, 18 Jun 2025 10:34:59 GMT

[quote user="simon884"]should I add to enable FPU for float also ?[/quote]

CONFIG_FPU should be enabled if you want to use and print floating point numbers.

RE: Trying to parse nmea with double and strtod

simon884 — Tue, 17 Jun 2025 15:12:58 GMT

No I can use float, but for example if instead of strtod I use strtof I have the same result for example:

if ((strcmp(&field[0][3], "VTG") == 0) && (f > 8)) {

      LOG_INF("Check string for strtod: '%s'", field[5]);
      for (int i = 0; i < strlen(field[5]); i++) {
          LOG_INF("field[5][%d] = 0x%02x", i, field[5][i]);
      }


      char tmp_kn[16] = {0};
      char tmp_kmh[16] = {0};
      strncpy(tmp_kn, field[5], sizeof(tmp_kn) - 1);  
      strncpy(tmp_kmh, field[7], sizeof(tmp_kmh) - 1);

      float ground_speed_kn = strtof(tmp_kn, NULL);
      float ground_speed_kmh = strtof(tmp_kmh, NULL);

      snprintf(str, sizeof(str), "speed knt : %.4f, speed kmh : %.4f", ground_speed_kn, ground_speed_kmh);
      LOG_INF("VTG %s", str);
}

I got in my terminal:

<inf> nmea_parser: #0 : $GNVTG
<inf> nmea_parser: #1 : 
<inf> nmea_parser: #2 : T
<inf> nmea_parser: #3 : 
<inf> nmea_parser: #4 : M
<inf> nmea_parser: #5 : 0.179
<inf> nmea_parser: #6 : N
<inf> nmea_parser: #7 : 0.331
<inf> nmea_parser: #8 : K
<inf> nmea_parser: #9 : A
<inf> nmea_parser: Check string for strtod: '0.179'
<inf> nmea_parser: field[5][0] = 0x30
<inf> nmea_parser: field[5][1] = 0x2e
<inf> nmea_parser: field[5][2] = 0x31
<inf> nmea_parser: field[5][3] = 0x37
<inf> nmea_parser: field[5][4] = 0x39
<inf> nmea_parser: VTG speed knt : 1043811264.0000, speed kmh : 1051293888.0000

So my nmea sentece seems to be good, my value also, but when i'm try to print I got bad value, should I add to enable FPU for float also ?

Edit: If I use sscanf instead of strtof everything works well...

RE: Trying to parse nmea with double and strtod

Hakon — Tue, 17 Jun 2025 07:56:21 GMT

Hello,

is CONFIG_FPU=y enabled in your application? Also, double values are not supported in hardware, but are emulated. Is there any specific reason why you don't just use regular float?