3.3V CMOS logics and Basic Stamp.

Archiver

Ciao,

I need to interface a 3.3V CMOS logic with my BS2p-24, both directions (some
lines as inputs, some others as outputs).

Did anybody experienced this kind of matching, and could suggest the best way?

Thanks in advance,

Alberto, IZ2EWV.


[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

In a message dated 4/18/2003 9:42:26 AM Pacific Daylight Time,
albertocalderara@t... writes:

> Ciao,
>
> I need to interface a 3.3V CMOS logic with my BS2p-24, both directions
> (some lines as inputs, some others as outputs).
>
> Did anybody experienced this kind of matching, and could suggest the best
> way?
>
> Thanks in advance,
>
> Alberto, IZ2EWV.
>


One very simple option is to use a 2n3904 NPN transitor.

FOR YOUR STAMP INPUTS>>>>>>>



Collector

---

10k
ohm

---

+5v
CMOS

---

470k ohm

---

Base<
Emitter

---

ground


The stamp input pin is connected to the collector.

When the CMOS output is "high" the stamp input will see a logic 0
When the CMOS output is "low" the stamp inpur will see a logic 1

There is an inversion (high = low) but that is the nice thing about software.

Quick calculations indicate the resistor values are OK, but if the CMOS high
does not produce .4 volts or less at the transistor collector, reduce the
value of the base resistor to 330k ohms.


The same circuit will work for your stamp output to make a 3.3 volts input to
your CMOS.
The only change you need to make to the circuit above is to connect the 10k
ohm resistor to 3.3 volts, and the collector of the transistor aslo goes to
the CMOS input.

If you need more details on how to hook this up, don't hesistate to write
back.

Ken


[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

In a message dated 4/18/2003 10:26:59 AM Pacific Daylight Time,
smartdim@a... writes:

THE FORMATTING GOT JACKED!!!!!!!!!! I will try to manipulate it and
repost.....

> One very simple option is to use a 2n3904 NPN transitor.
>
> FOR YOUR STAMP INPUTS>>>>>>>
>
>
> HOPEFULLY A FIXED VERSION BELOW
>
> Collector||10kohm||+5v
> CMOS||470kohm||Base<
> Emitter||ground
>
>
> The stamp input pin is connected to the collector.
>
> When the CMOS output is "high" the stamp input will see a logic 0
> When the CMOS output is "low" the stamp inpur will see a logic 1
>
> There is an inversion (high = low) but that is the nice thing about
> software.
>
> Quick calculations indicate the resistor values are OK, but if the CMOS
> high
> does not produce .4 volts or less at the transistor collector, reduce the
> value of the base resistor to 330k ohms.
>
>
> The same circuit will work for your stamp output to make a 3.3 volts input
> to
> your CMOS.
> The only change you need to make to the circuit above is to connect the 10k
>
> ohm resistor to 3.3 volts, and the collector of the transistor aslo goes to
>
> the CMOS input.
>
> If you need more details on how to hook this up, don't hesistate to write
> back.
>
> Ken
>



[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

Thanks Ken for the help.

It was indeed the kind of solution I was thinking about. But I was also
wandering if - since 3.3V CMOS family is a growing-up industry standard - there
was some kind of buffer including in its package a certain number of 5V to 3.3V
and/or vice-versa translators, like happened for example between TTL and CMOS
families.

Maxim has recently introduced a VFD controller family (for both 8-14-16 segment
and 5x7 dot matrix digits) - namely MAX6850

Archiver

In a message dated 4/19/2003 2:14:46 AM Pacific Daylight Time,
albertocalderara@t... writes:

> Thanks Ken for the help.
>
> It was indeed the kind of solution I was thinking about. But I was also
> wandering if - since 3.3V CMOS family is a growing-up industry standard -
> there was some kind of buffer including in its package a certain number of
> 5V to 3.3V and/or vice-versa translators, like happened for example between
> TTL and CMOS families.
>
> Maxim has recently introduced a VFD controller family (for both 8-14-16
> segment and 5x7 dot matrix digits) - namely MAX6850

Archiver

>Thanks Ken for the help.
>
>It was indeed the kind of solution I was thinking about. But I was
>also wandering if - since 3.3V CMOS family is a growing-up industry
>standard - there was some kind of buffer including in its package a
>certain number of 5V to 3.3V and/or vice-versa translators, like
>happened for example between TTL and CMOS families.


The CMOS CD4050 and CD4049 are level translators that were initially
for translation from ~10 volt CMOS levels down to 5 volt TTL levels,
but they also work fine at Stamp speeds for output translation from 5
volts to 3 volts.

Stamp inputs (1.5 volt switching threshold) work fine with 0 to 3
volt input--no translation necessary.