reading 24bits

gtslabs

I finally got my AD7730 to run. I see that the variable "WORD" is 16 bits. How do I set up a variable to receive 24 bits of decimal values?

Also,· how would I stream this in Visal Basic? Would I have to loop until I get the "CR" ascii code I have at the end·of my Debug line?

Thanks
Steve

Mike Green

There are no variables larger than 16 bits although you can declare arrays and a 3 byte array would be 24 bits. The problem is that there's no 24 bit arithmetic. You can do the I/O in multiples of 8 bits just by providing multiple byte variables in the SHIFTIN statement that you're probably using. If you want to output this to Visual Basic you'll have to either write your own 24 bit binary to decimal conversion routine or possibly output it in hex since you can catenate the 3 8-bit values so they look like one 24-bit value to VB (if it can receive hex ... I haven't used it enough to know).