Help with strings
Posted: Fri Mar 30, 2018 7:13 pm
Hello,
This post is a request for help using painlessMesh, but it is to do with string manipulation above all else.
I am creating a character array of 65536 elements representing 32784 ADC readings.
The ADC read routine is
The loop increments by 2 each time.
As the ADC is 12 bits, I encode each value to 2 ascii characters using this function to ensure certain character values are avoided
This results in an array of ascii characters from 40 to 52 and 57 to 109 avoiding problematic characters in JSON.
I want to send the data in 128 packets of 512 characters using the painlessMesh library. So I need to put the first 512 characters into a String (followed by further 512 char packets) called pkt so I can send it out over WiFi using
I have tried using
with pkt declared as a String and the code compiles and runs but doesnt work. I have also tried the same declaring pkt as char[513] and char* but both of those have errors at compile time.
If I replace the above code with pkt = "Anything at all", it works and me seconde ESP32 reports an incoming message perfectly. Where am I going wrong?
Please help, Im going insane trying to work it out! Steve.
This post is a request for help using painlessMesh, but it is to do with string manipulation above all else.
I am creating a character array of 65536 elements representing 32784 ADC readings.
The ADC read routine is
Code: Select all
rdg=analogRead(ADC0);
twf[a]=(char)encoder((int(rdg/64)));
twf[a+1]=(char)encoder((int(rdg%64)));As the ADC is 12 bits, I encode each value to 2 ascii characters using this function to ensure certain character values are avoided
Code: Select all
int encoder(int data){
if (data < 52)
return data + 40;
else
return data + 45;
}I want to send the data in 128 packets of 512 characters using the painlessMesh library. So I need to put the first 512 characters into a String (followed by further 512 char packets) called pkt so I can send it out over WiFi using
Code: Select all
mesh.sendBroadcast(pkt);Code: Select all
for(a=0; a<512; a++)
pkt[a]=twf[a];
pkt[512]='\0';If I replace the above code with pkt = "Anything at all", it works and me seconde ESP32 reports an incoming message perfectly. Where am I going wrong?
Please help, Im going insane trying to work it out! Steve.