Decoding 2 bit to 4
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Does anyone know of an IC that EXACTLY matches this truth table:
IN OUT
| a b | 1 2 3 4 |
|
|
|
| 0 0 | 1 0 0 0 |
| 0 1 | 0 1 0 0 |
| 1 0 | 0 0 1 0 |
| 1 1 | 0 0 0 1 |
The 74x195 & 74x155 have the outputs reversed from this, and I would have to
use a set of inverters, and i REALLY needed to keep the # of devices to a
minimum. So, if anyone knows of a device...
Thanks in advance,
Edward Kindler
IN OUT
| a b | 1 2 3 4 |
|
|
|
| 0 0 | 1 0 0 0 |
| 0 1 | 0 1 0 0 |
| 1 0 | 0 0 1 0 |
| 1 1 | 0 0 0 1 |
The 74x195 & 74x155 have the outputs reversed from this, and I would have to
use a set of inverters, and i REALLY needed to keep the # of devices to a
minimum. So, if anyone knows of a device...
Thanks in advance,
Edward Kindler
Comments
CD4028 is straightforward.
CD4514 can do this using q8 q9 q10 q11 as outputs and setting A3 High.
The CD4051 8ch analog multiplex is OK (must use pull up /or down
resistors ? ).
ACJacques
RiffRaff82@a... wrote:
>
> Does anyone know of an IC that EXACTLY matches this truth table:
>
> IN OUT
> | a b | 1 2 3 4 |
> |
|
|
> | 0 0 | 1 0 0 0 |
> | 0 1 | 0 1 0 0 |
> | 1 0 | 0 0 1 0 |
> | 1 1 | 0 0 0 1 |
>
> The 74x195 & 74x155 have the outputs reversed from this, and I would have to
> use a set of inverters, and i REALLY needed to keep the # of devices to a
> minimum. So, if anyone knows of a device...
>
> Thanks in advance,
> Edward Kindler
the rest of your circuit). If you can't find one, try a 74X238 and ground
the extra input (and ignore the extra outputs).
Regards,
Al Williams
AWC
* Floating point math for the Stamp, PIC, SX, or any microcontroller at
http://www.al-williams.com/awce/pak1.htm
>
Original Message
> From: RiffRaff82@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=jvWyjfxKGI1Pq3_J7utIE8kGdEQeGu9C2CL8JHa1YFV9D9ujp2QGUtJryOytUZJlUxFz1LiGirw]RiffRaff82@a...[/url
> Sent: Sunday, August 06, 2000 6:51 PM
> To: SeattleRobotics@egroups.com; basicstamps@egroups.com
> Subject: [noparse][[/noparse]basicstamps] Decoding 2 bit to 4
>
>
> Does anyone know of an IC that EXACTLY matches this truth table:
>
> IN OUT
> | a b | 1 2 3 4 |
> |
|
|
> | 0 0 | 1 0 0 0 |
> | 0 1 | 0 1 0 0 |
> | 1 0 | 0 0 1 0 |
> | 1 1 | 0 0 0 1 |
>
> The 74x195 & 74x155 have the outputs reversed from this, and I
> would have to
> use a set of inverters, and i REALLY needed to keep the # of devices to a
> minimum. So, if anyone knows of a device...
>
>
> Thanks in advance,
> Edward Kindler
>
>
>Does anyone know of an IC that EXACTLY matches this truth table:
>
> IN OUT
>| a b | 1 2 3 4 |
>|
|
|
>| 0 0 | 1 0 0 0 |
>| 0 1 | 0 1 0 0 |
>| 1 0 | 0 0 1 0 |
>| 1 1 | 0 0 0 1 |
>
>The 74x195 & 74x155 have the outputs reversed from this, and I would have to
>use a set of inverters, and i REALLY needed to keep the # of devices to a
>minimum. So, if anyone knows of a device...
Either of the following decoders will ehibit the outputs you desire:
CD4028 National HEF4028 Philips
Both are BCD to Decimal, or Binary to Octal - Decoders. Both are a bit of
overkill, as they are wider than necessary, but so it is with 4-bit
requirements.
The National part has 4 input buffers and 10 output buffers (2/4, 3/8,
4/10). Not sure about the Philips unit.
>Thanks in advance,
>Edward Kindler
Surely
Regards,
Bruce Bates
>What you want is a 74X239 (where X is HC, L, F, whatever you need to match
>the rest of your circuit). If you can't find one, try a 74X238 and ground
>the extra input (and ignore the extra outputs)
Just for the record, the CD74xx238 is available from TI, and the 239 is
obso and only available from Rochester.
Regards,
Bruce Bates
>.
>
>Regards,
>
>Al Williams
>AWC
>* Floating point math for the Stamp, PIC, SX, or any microcontroller at
>http://www.al-williams.com/awce/pak1.htm
>
> >
Original Message
> > From: RiffRaff82@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=yrizUp65W6MeiQaxXi36OeyxpR8sfzpmi9IVgYhyPn6EvuPzcNo2fPDftzV88IVaEtwgnnV6vGt5aFhdJw]RiffRaff82@a...[/url
> > Sent: Sunday, August 06, 2000 6:51 PM
> > To: SeattleRobotics@egroups.com; basicstamps@egroups.com
> > Subject: [noparse][[/noparse]basicstamps] Decoding 2 bit to 4
> >
> >
> > Does anyone know of an IC that EXACTLY matches this truth table:
> >
> > IN OUT
> > | a b | 1 2 3 4 |
> > |
|
|
> > | 0 0 | 1 0 0 0 |
> > | 0 1 | 0 1 0 0 |
> > | 1 0 | 0 0 1 0 |
> > | 1 1 | 0 0 0 1 |
> >
> > The 74x195 & 74x155 have the outputs reversed from this, and I
> > would have to
> > use a set of inverters, and i REALLY needed to keep the # of devices to a
> > minimum. So, if anyone knows of a device...
> >
> >
> > Thanks in advance,
> > Edward Kindler
> >
> >
Norm & Monda
Cozy MK IV #202
Ford V-6 Powered
Original Message
From: "Bruce Bates" <bvbates@u...>
To: <basicstamps@egroups.com>
Sent: Monday, August 07, 2000 1:06 AM
Subject: Re: [noparse][[/noparse]basicstamps] Decoding 2 bit to 4
> At 07:51 PM 8/6/00, you wrote:
> >Does anyone know of an IC that EXACTLY matches this truth table:
> >
> > IN OUT
> >| a b | 1 2 3 4 |
> >|
|
|
> >| 0 0 | 1 0 0 0 |
> >| 0 1 | 0 1 0 0 |
> >| 1 0 | 0 0 1 0 |
> >| 1 1 | 0 0 0 1 |
> >
> >The 74x195 & 74x155 have the outputs reversed from this, and I would have
to
> >use a set of inverters, and i REALLY needed to keep the # of devices to a
> >minimum. So, if anyone knows of a device...
>
> Either of the following decoders will ehibit the outputs you desire:
>
> CD4028 National HEF4028 Philips
>
> Both are BCD to Decimal, or Binary to Octal - Decoders. Both are a bit of
> overkill, as they are wider than necessary, but so it is with 4-bit
> requirements.
> The National part has 4 input buffers and 10 output buffers (2/4, 3/8,
> 4/10). Not sure about the Philips unit.
>
>
>
> >Thanks in advance,
> >Edward Kindler
>
> Surely
>
> Regards,
>
> Bruce Bates
>
>
>
>
>
>
> 74138 or equiv, decodes 3 bits, tie 1 bit off (low)
>
> Norm & Monda
74138 outputs are INVERTED of required.
ACJacques
>
> > At 07:51 PM 8/6/00, you wrote:
> > >Does anyone know of an IC that EXACTLY matches this truth table:
> > >
> > > IN OUT
> > >| a b | 1 2 3 4 |
> > >|
|
|
> > >| 0 0 | 1 0 0 0 |
> > >| 0 1 | 0 1 0 0 |
> > >| 1 0 | 0 0 1 0 |
> > >| 1 1 | 0 0 0 1 |
> > >
> > >The 74x195 & 74x155 have the outputs reversed from this, and I would have
> to
> > >use a set of inverters, and i REALLY needed to keep the # of devices to a
> > >minimum. So, if anyone knows of a device...
Norm & Monda
Cozy MK IV #202
Ford V-6 Powered
Original Message
From: "A.C.Jacques" <acjacques@i...>
To: <basicstamps@egroups.com>
Sent: Monday, August 07, 2000 8:15 AM
Subject: Re: [noparse][[/noparse]basicstamps] Decoding 2 bit to 4
> norm doty wrote:
> >
> > 74138 or equiv, decodes 3 bits, tie 1 bit off (low)
> >
> > Norm & Monda
>
> 74138 outputs are INVERTED of required.
> ACJacques
>
> >
> > > At 07:51 PM 8/6/00, you wrote:
> > > >Does anyone know of an IC that EXACTLY matches this truth table:
> > > >
> > > > IN OUT
> > > >| a b | 1 2 3 4 |
> > > >|
|
|
> > > >| 0 0 | 1 0 0 0 |
> > > >| 0 1 | 0 1 0 0 |
> > > >| 1 0 | 0 0 1 0 |
> > > >| 1 1 | 0 0 0 1 |
> > > >
> > > >The 74x195 & 74x155 have the outputs reversed from this, and I would
have
> > to
> > > >use a set of inverters, and i REALLY needed to keep the # of devices
to a
> > > >minimum. So, if anyone knows of a device...
>
>
>