putc and printf

micro_man · Joined: 05 Jun 2013 Posts: 14

Hi,
I have a very simple query. I want to send a number using serial port.
e.g

Ttelmah · Joined: 11 Mar 2010 Posts: 19448

Probably not.

Your %x, prints the number in hexadecimal. If you number gets to 10 (decimal), it'll output as 0a. Is this what you want?....

Start at the beginning '1' (number), sent using putc, is the ASCII character 'SOH' which means 'start of heading'. Not the number '0' (this is ASCII 0x31).
You don't want to use putc to send numbers unless you have already turned them into ASCII.

Printf will turn number into ASCII for you. %d does this exactly as you have found, but '1', is the digit "1", not the two digits "01". The answer to this is in the manual for printf (read a C textbook which will explain much more). You can use: %02d which says 'print this result in a field 2 digits wide, with leading zero(s)'. So:

printf("%02d",a);

will output "01", and when 'a' gets to 10, will output "10". When a is '0' this will output "00".

Probably what you want.