Re: Can I connect TTL devices together.
- --- In email@example.com, "Barbudor" <barbudor@...> wrote:
>If you look at the stowaway hardware reference manual [http://www.splorp.com/pdf/
> What make you think the Stowaway is TTL ?
stowawayhwref.pdf] it stats that the Handspring edition of the keyboard is TTL look at
> It connects to a PALM and on my PALM IIIxGood because VCC of the Stowaway can be 3.0V DC to 5.5V DC.
> the serial connection is direct to PC RS232, without any
> Did you just measured signals ? Don't conclude that it is TTL
> just becuase the signal range is 0..5V. It may just be because
> it use a tolrance of the PALM input.
> TTL serial use a positive logic while RS232 use negative logic:
> - for a 0 bit, TTL is at 0V and RS232 is at +3..12V
> - for a 1 bit, TTL is at 5V and RS232 is at -3..12V
> A TTL/RS232 converter is basicaly a inverter + voltage shifter.
> Note that default state and stop bit is 1, start bit is 0.
> By the Way the ZipIt is not TTL but LVTTL at 3.3V
>I will look into that.
> So I feel that you will need an simple inverter such as a 74LV07
> so they talk the same logic.
>Thank. It got my brain going again. I almost still think that I should convert both to serial,
> Note that this is very quick thoughts. Did not even looked back
> at the PALM schematics.
just so I have have the serial port.
> ----- Original Message -----
> From: "Silas" <silas.baronda@...>
> To: <firstname.lastname@example.org>
> Sent: Thursday, July 05, 2007 4:53 PM
> Subject: [zipitwireless] Can I connect TTL devices together.
> I have a TTL keyboard that I want to adapt to the zipit. If the zipit
> is already TTL can I just connect the keyboard directly to the zipit
> because it is TTL?
> If not, would I have to convert each device to rs-232 and then connect
> the serial port together?
> P.S. I'm trying to connect a Visor Storaway keyboard to my zipit.