[sci.electronics] I need a serial data decoder that....

buzz@phoenix.Princeton.EDU (Mahboud Zabetian) (03/23/88)

----- News saved at 23 Mar 88 02:33:11 GMT

I have serial data coming in between 1200-9600 baud(I can determine the value).
I want to have a circuit display the value of each serially transmitted byte.

This is what I have right now:

serial data coming in   ----> MC14411(xtall controlled clock)  -->
				 MC6850(UART)  --> Two 7 segment displays

Things work fine, but I have to program a value of 0x15 into the MC6850 each
time I powerup my circuit.

Can anyone tell me if there is a better way to do this?

(The data coming in will come a byte at a time and there are pretty long delays
between each byte(>1second);  I want the two seven segment displays to show the
byte till the next byte arrives)

Thank you for your help. 
-- 
Mahboud Zabetian				buzz@phoenix.princeton.edu
183 Little Hall 					(609) 520-1271
Princeton University, Princeton, NJ 08544		(609) 734-7760
****** Anyone need a soon-to-graduate hardware/software engineer? ********
-- 
Mahboud Zabetian				buzz@phoenix.princeton.edu
183 Little Hall 					(609) 520-1271
Princeton University, Princeton, NJ 08544		(609) 734-7760
****** Anyone need a soon-to-graduate hardware/software engineer? ********

henry@utzoo.uucp (Henry Spencer) (03/24/88)

> Things work fine, but I have to program a value of 0x15 into the MC6850 each
> time I powerup my circuit.

What you want, I should think, is an old-style UART that brings all its
control functions out to pins, as opposed to the modern ones that are all
microcomputer-bus-oriented and have to be programmed.  I think you can
still get the old ones! :-)
-- 
"Noalias must go.  This is           |  Henry Spencer @ U of Toronto Zoology
non-negotiable."  --DMR              | {allegra,ihnp4,decvax,utai}!utzoo!henry

sfs@panda.UUCP (Stephen F. Santarelli) (03/24/88)

>I have serial data coming in between 1200-9600 baud
>I want to have a circuit display the value of each serially transmitted byte.
>This is what I have right now:

>serial data coming in   ----> MC14411(xtall controlled clock)  -->
>				 MC6850(UART)  --> Two 7 segment displays


>Can anyone tell me if there is a better way to do this?

    The chip you are using was intended for use with a microprocessor type
bus (i.e. data, address & control lines).  Why not use a real UART such
as a 6402(MOSTEK)? This should minimize your hardware considerably.  

    Have you considered what you will use to decode the parallel data
(presumably ASCII) so that it will appear in some sort of readable form
on your displays?  Perhaps you might divide the 8-bits into 3 octal digits
(the most significant would only have two bits, of course), each using a
separate 7447 to decode binary to 7-segment.  Or, maybe, use an 8-bit
binary to 3-digit bcd converter(two 74185), once again with 3 7447's
and 3 displays.  Or, if you can find one, possibly a chip which could
drive two 7-segment displays with hex symbols (If somebody knows of one,
let me know).  These chips should all be found in the TTL data book.

	Good Luck

		Stephen Santarelli de Brasch
      

buzz@phoenix.Princeton.EDU (Mahboud Zabetian) (03/25/88)

>and 3 displays.  Or, if you can find one, possibly a chip which could
>drive two 7-segment displays with hex symbols (If somebody knows of one,
>let me know).  These chips should all be found in the TTL data book.

I am using two displays that can handle hex characters.  They already have the
logic on the chip.  As input each takes four lines (D0-D3).

Don't know what the display number or type is, but if you really want I can
find out.

Oh, and thank you.

-- 
Mahboud Zabetian				buzz@phoenix.princeton.edu
183 Little Hall 					(609) 520-1271
Princeton University, Princeton, NJ 08544		(609) 734-7760
****** Anyone need a soon-to-graduate hardware/software engineer? ********

byron@pyr.gatech.EDU (Byron A Jeff) (03/26/88)

In article <3506@panda.UUCP< sfs@panda.UUCP (Stephen F. Santarelli) writes:
<
<
<>I have serial data coming in between 1200-9600 baud
<>I want to have a circuit display the value of each serially transmitted byte.
<>This is what I have right now:
<
<>serial data coming in   ----> MC14411(xtall controlled clock)  -->
<>				 MC6850(UART)  --> Two 7 segment displays
<
<
<>Can anyone tell me if there is a better way to do this?
<
<    The chip you are using was intended for use with a microprocessor type
<bus (i.e. data, address & control lines).  Why not use a real UART such
<as a 6402(MOSTEK)? This should minimize your hardware considerably.  
<
<    Have you considered what you will use to decode the parallel data
<(presumably ASCII) so that it will appear in some sort of readable form
<on your displays?  Perhaps you might divide the 8-bits into 3 octal digits
<(the most significant would only have two bits, of course), each using a
<separate 7447 to decode binary to 7-segment.  Or, maybe, use an 8-bit
<binary to 3-digit bcd converter(two 74185), once again with 3 7447's
<and 3 displays.  Or, if you can find one, possibly a chip which could
<drive two 7-segment displays with hex symbols (If somebody knows of one,
<let me know).  These chips should all be found in the TTL data book.
<
<	Good Luck
<
<		Stephen Santarelli de Brasch
<      

One chip that does what you ask is a 9368. Unfortunately I don't know
who manufactures it. It only drives a single display but I've built
a board that multiplexed 10 displays. It has ripple blanking and
latches its data.

BAJ

markz@ssc.UUCP (Mark Zenier) (03/26/88)

In article <3506@panda.UUCP>, sfs@panda.UUCP (Stephen F. Santarelli) writes:
> ... Or, if you can find one, possibly a chip which could
> drive two 7-segment displays with hex symbols (If somebody knows of one,
> let me know). ... 

If you want to display 1 hex digit, the Fairchild 9368, 9369, 9370 (old! TTL)
and the Motorola Mc14495-1 (cmos) will do that. You may find that burning 
your own PAL is cheaper.

Mark Zenier

tomb@hplsla.HP.COM ( Tom Bruhns) (03/26/88)

>  . . .   Or, if you can find one, possibly a chip which could
> drive two 7-segment displays with hex symbols (If somebody knows of one,
> let me know).  These chips should all be found in the TTL data book.
> 
> Good Luck
> 
>    Stephen Santarelli de Brasch
      
----------
How about an LED display which has the decoder-driver built-in (for hex)?
Like the TIL-311, I believe, or one of the ones my employer sells. . .

mitch@mandrill.CWRU.Edu (Mitchell Perilstein) (03/27/88)

>I have serial data coming in between 1200-9600 baud(I can determine the value).
>I want to have a circuit display the value of each serially transmitted byte.
....
>Can anyone tell me if there is a better way to do this?

There are many one-chip CPU's such as the 6511, 68701, 8748, etc. that have
a familiar processor as their core but also have various peripherals, timers, 
memories, and so on.

I've been using the 68701, it has a serial port you can read your data in with,
and has four parallel ports you can use to control a display (even an un-
encoded seven-segment one--just write a program), and some internal RAM and 
EPROM. The processor is a 6800, which has an easy instruction set to learn.

Your display unit would be basically one chip, with driving transistors or
something for the display, if needed.

-------------------------------------------------------------------------------
Mitchell Perilstein                       |  Give me but one spot on which to
{...decvax}!mandrill!mitch                |  stand, and I shall move the Earth!
-------------------------------------------------------------------------------

rmf@actnyc.UUCP (Robert M. Fuhrer) (04/01/88)

On a somewhat related topic, I heard about a chip (manufacturer unknown)
which had a microprocessor, some D/A or A/D circuitry, and possibly some RAM
and ROM.  The part number I recall is something like 8520.  At the time, I
looked to several distributors, with no luck.  Since then, I have gotten a
bit fuzzier on the number... Anybody have any info on this sucker?