Perhaps it is a case of the 1 PPS pulse
being too narrow?
some GPS's have a very narrow 1 PPS, others wider; there is no
standard.
Levels are probably OK, perhaps you need to build a pulse
stretcher?
cheers, Graham ve3gtc
On 13-08-06 09:31 AM, Steph Spirat wrote:
toggle quoted message
Show quoted text
Hi Andy,
No, haven't tried with NMEA input - awaiting arrival of level
converter pcb to convert the rs232 serial to TTL. I could knock
up a one transistor level convertor (and not be lazy!) and then
try giving that a go, too. I was led to believe from the
instructions that I shouldn't need to include GPS input if I
don't need grid locator or time? (Just looking to keep time
(tics) in sync).
The ATMega 168 is 5v device (hence, connected to 5v. 20MHz
version, 4.5 to 5.5v). PC5 is a bi-directional port with
internal pull-up resistors, that may or may not be enabled
(programmed) If configured as an input, I'm not sure if it is
looking for a particular level transistion and/or whether, as
you've suggested, that it is looking for a NMEA string to rip
the initial time from?? Perhaps Hans can update us on what
actually happens here??
Cheers,
Thanks for the suggestion,. Will give it a try , when time
permits.....!
Steph
