Your checksumCalc variable can overflow. You need to mask it with 0x0f otherwise the checksum comparison will fail eventhough it matches.

unsigned int checksumCalc = 0;
checksumCalc += (winddir & 0x0f);
checksumCalc += ((windspeed >> 8) & 0x0f);
checksumCalc += ((windspeed >> 4) & 0x0f);
checksumCalc += (windspeed & 0x0f);

You need to add:

checksumCalc &= 0x0f;

Correggere TTLib.py per un corretto aggiornamento dati "umidità" e pioggia in APRS; le correzioni da apportare sono:

humidity

if (globalvars.meteo_data.hum_out != None):
    rh = float(globalvars.meteo_data.hum_out / 100 )
    if rh >= 0.995:
        humid_str = "h00"
    else:

humid_str = "h" + "%02.0f" % (rh * 100.0)

        humid_str = "h" + "%02.0f" % (globalvars.meteo_data.hum_out)
    send += humid_str

rain last hour -- each count is 0.0204"

if (globalvars.meteo_data.rain_rate_1h != None):
    rain_hr_hundredth_inches = float(globalvars.meteo_data.rain_rate_1h * 3.9370078)
    rain_hr_str = "r" + "%03d" % rain_hr_hundredth_inches

rain_hr_str = "r" + int(globalvars.meteo_data.rain_rate_1h)

    send += rain_hr_str

# rain last 24 hours -- each count is 0.0204"
# so the math accidentally scales perfect -- report in hundreths of inches
if (globalvars.meteo_data.rain_rate_24h != None) :
    rain_24_hrs_hundredth_inches = float(globalvars.meteo_data.rain_rate_24h * 3.9370078)
    rain_24_hrs_str = "p" + "%03d" % rain_24_hrs_hundredth_inches

rain_24_hrs_str = "p" + int(globalvars.meteo_data.rain_rate_24h)

    send += rain_24_hrs_str

skip rain since midnight

if (globalvars.meteo_data.rain_rate != None ) :
    rain_today_hundredth_inches = float(globalvars.meteo_data.rain_rate  * 3.9370078)
    rain_midnight_str = "P" + "%03d" % rain_today_hundredth_inches
    send += rain_midnight_str

Hello,

I connect a TX23 Wind Sensor to Raspberry (latest Rasbian) and use your code to get data.
Next to the Sensor I placed a small Fan to get stable wind speed and fixed the direction sensor to
have always the same value for testing.

When i try to use ./readTX23 -v i get data like followed (try differend times over a time of lets say 10 minutes?)

root@raspberrypi:/home/wetter/swpi/TX23# ./readTX23 -v

Bit Length: 1225 uSec
Start frame: 27
Wind Direction: W (12)
Wind Direction2: W (12)
Wind Speed: 7
Wind Speed2: 7
Checksum (received): 3
Checksum (calculated): 19

Data is NOT Valid!

root@raspberrypi:/home/wetter/swpi/TX23# ./readTX23 -v

Bit Length: 1225 uSec
Start frame: 27
Wind Direction: W (12)
Wind Direction2: W (12)
Wind Speed: 8
Wind Speed2: 8
Checksum (received): 4
Checksum (calculated): 20

Data is NOT Valid!

root@raspberrypi:/home/wetter/swpi/TX23# ./readTX23 -v

Bit Length: 1225 uSec
Start frame: 27
Wind Direction: W (12)
Wind Direction2: W (12)
Wind Speed: 9
Wind Speed2: 9
Checksum (received): 5
Checksum (calculated): 21

Data is NOT Valid!

root@raspberrypi:/home/wetter/swpi/TX23# ./readTX23 -v

Bit Length: 1225 uSec
Start frame: 27
Wind Direction: W (12)
Wind Direction2: W (12)
Wind Speed: 9
Wind Speed2: 9
Checksum (received): 5
Checksum (calculated): 21

Data is NOT Valid!

root@raspberrypi:/home/wetter/swpi/TX23# ./readTX23 -v

Bit Length: 1225 uSec
Start frame: 27
Wind Direction: W (12)
Wind Direction2: W (12)
Wind Speed: 9
Wind Speed2: 9
Checksum (received): 5
Checksum (calculated): 21

Data is NOT Valid!

First of all whats the messure of wind speed?
If it is m/s why it is an integer?
Why i get always the same discalculated checksum?
I overclock my raspberry I don't know if it is a problem for this code (e.g. the timer)?

I'am an bloody beginer @hardware codeing.
I also ask the author of source code but he didn't answer so I hope you can please help me.
Thanks a lot.

Hi Tonino,
thanks for making this huge program available.
i want to use this program with my La Crosse TX-23U device.

i am getting this error message after runnning:
sudo python swpi.py

File "/home/pi/swpi-master/TTLib.py", line 15, in
import Image
ImportError: No module named Image

where is Image.py located ???