[ntp:questions] Sure GPS: Programming it now works

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Tue Apr 5 18:06:02 UTC 2011

unruh wrote:
> On 2011-04-05, Terje Mathisen<"terje.mathisen at tmsw.no">  wrote:
>> I haven't tried without, and it does protect against some line errors,
>> so why not?
> because if you are generating the lines by hand and sending it to the
> chip via say minicom with the Y option, calculating the checksum is not
> trivial. By the way is it everything between the $ and the * or does it
> include the $ and *?

I think I'll make a trivial addition to my little hack:

An option to send an arbitrary command:

Something like
  -p port (default COM1)
  -b baud (default 9600)
  -s string (send $string*xxCRLF to mtk

>> The calculation is after all really trivial:
>> 	len = strlen(buffer);
>> 	// Add trailing '*' if missing:
>> 	if (buffer[len-1] != '*')
>> 		buffer[len++] = '*';
>> 	// XOR sum of all bytes, except the first and last:
> OK, you are saying, omit the $ and *



- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

More information about the questions mailing list