CODEWITHSUNDEEP
cbit-manipulationraspberry-piascii
SerialMadMan
SerialMadMan

Reputation: 1

C Binary Stream

I have got a raspberry pi bit banging at 1.25MBaud on the GPIO pins. The raspberry pi is to emulate an end system in a RS485 communications network. So hopefully that is the physical layer working :)

I am now struggling with the application layer. The c code libraries require Ascii for example "Hello, world!". It would be desirable for me to pass a binary stream ie "111010111010001010111", there will be 5814 bits :) so I have been researching how to convert binary to ascii however only found complicated c++ answers. Does anyone have a simple solution? Thanks for your help!

Paul

Upvotes: 0

Views: 256

Answers (2)

olegarch
olegarch

Reputation: 3891

For move 7-bits ASCII-char to the port bit-by-bit, you can use:

void toPort(unsigned char x) {
  x |= 0200; // Set unused high-bit to 1
  for ( ; ; ) {
   char bit = x & 1;
   x >>= 1;
   if(x == 0) return;
   push_to_port(bit);
  } 
}

Upvotes: 0

AnthonyLambert
AnthonyLambert

Reputation: 8830

Apparently you don't need to break the string into bits the API does it for you....

Anyway if you did:

Each char in your "hello world\n" string is a byte when encoded in ASCII. ASCII actually only used the lowest 7 bits. If you want to pick apart a char into bits I would use the following code as a start.

char ch = 'h';
for (i=0; i<7; i++) {
   bool b = (ch & 1 == 1);
   ch >>= 1;
   // set the bit value b off to the pin....
   }

you would need a loop around this to process whole strings.

Upvotes: 1

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