[aprssig] GPS GT-320FW(AS)

Steve Noskowicz noskosteve at yahoo.com
Sun Apr 21 18:03:50 CDT 2013


Yea.  That datasheet is woefully light on it's info.  Interesting since I would "tend" to believe the TTL levels it has are the phase that is inverted from RS232.  This would make for simple interfacing with local logic without requiring two a 232 level converters.

...  but you never know.  The UniTraQ site is no better with dead links to datasheets. ... sigh...

Surely Scott will chime it...


A large majority of RS-232 receivers have a threshold in the Plus 1-2 volt range which means you can drive them with a TTL inverter instead of a MAX232 kind of solution.  So they are "TTL compatible", but not in the common TTL phase.  YMMV

  I'm also interested in learning what "low voltage" TTL is.  I'm guessing 3.3v.

73, Steve, K9DCI  USN (Vet)  MOT (Ret)  Ham (Yet)

P.S. The logic levels for garden variety TTL (LS & some others) running on 5 volts are 0 and 3.5 volts, not 0 and 5 volts, though there are exceptions and many ways to interface that yield 0 and 5 volts - to which it is tolerant.

73, Steve, K9DCI



--- On Sun, 4/21/13, Andrew Rich <vk4tec at tech-software.net> wrote:

> From: Andrew Rich <vk4tec at tech-software.net>
> Subject: Re: [aprssig] GPS GT-320FW(AS)
> To: "Jason KG4WSV" <kg4wsv at gmail.com>
> Cc: "TAPR APRS Mailing List" <aprssig at tapr.org>
> Date: Sunday, April 21, 2013, 9:20 AM
> And more importantly the phase of the
> TTL
> 
> There's RS232 -7 / +7 volts
> There's sudo RS232 0 / 5 volts
> 
> Then there is USART compatible which is sudo RS232 upside
> down 
> 
> Sent from my iPhone
> Andrew Rich
> 
> On 21/04/2013, at 11:06 PM, Jason KG4WSV <kg4wsv at gmail.com>
> wrote:
> 
> > The datasheet indicates it has both TTL level and RS232
> level
> > depending on which set of pins you use.
> > 
> > What isn't clear is the TTL voltage level - is it 3.3V
> TTL? 5V?  3.3V
> > but 5V tolerant?
> > 
> > -Jason
> > kg4wsv
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