BCD to Binary Conversion

[K Wind]

Let's say I have a couple of BCD counters (CD4510) with thumbwheel switches
connected to the preset inputs and a couple of binary counters (74193)
sharing a common clock with the 4510s. If I initially reset all counters,
preset the 4510s and count down to zero while having the 74193s count up,
have I converted the numbers indicated on the thumbwheel switches to binary?
It seems like this would work, but would like input from others.

Ken

 

[K Wind]

It's simply an (E)EPROM with parallel address inputs/outputs (some are
serial for special purposes like programming FPGAs).


The address is the code to be converted from and the data at that
address is the code to be converted to.

Thanks for the info.

Ken

 

[Tom Del Rosso]

It would work. You could also use a parallel EPROM/EEPROM or a
microcontroller for a single-chip solution.

I think you might add that it will work as long as the pulses are clean.
No pulses too short for the CMOS counter, nor too low for the CMOS
threshold, which is being clocked in parallel with a TTL counter, nor
any noise that might trigger the TTL.

 

[Spehro Pefhany]

I think you might add that it will work as long as the pulses are clean.
No pulses too short for the CMOS counter, nor too low for the CMOS
threshold, which is being clocked in parallel with a TTL counter, nor
any noise that might trigger the TTL.

If we start adding caveats we might be here all night, but it's
perhaps worth noting that those CMOS CD4510 parts are glacially slow
at 5V (2MHz). Not much drive either, so using HC193's might be an
idea.


Best regards,
Spehro Pefhany

 

[K Wind]

I think you might add that it will work as long as the pulses are clean.
No pulses too short for the CMOS counter, nor too low for the CMOS
threshold, which is being clocked in parallel with a TTL counter, nor
any noise that might trigger the TTL.

Thanks for the info. The clock would be around 10KHz to 100KHz and made of
CMOS inverters or a 4093. The maximum number of counters would be four each.
I haven't looked at any specs on how many TTL devices can be driven by
whatever device would be used for the clock, but will when the time comes. I
will also look at what is required by the 74193s.

Ken

 

[K Wind]

If we start adding caveats we might be here all night, but it's
perhaps worth noting that those CMOS CD4510 parts are glacially slow
at 5V (2MHz). Not much drive either, so using HC193's might be an
idea.

In this application, I won't be driving anything with the 4510s. All they do
is determine how many clock ticks are sent to the 74193s. I will be
monitoring the "carry in" to determine when all the 4510s have counted down
to zero and then shut off the clock. Both the 4510s and the 74193s will be
have a common clock. Whatever I use to implement the clock will have to
drive all of the counters.

I must confess that I am on a very tight budget here and have to use what I
have on hand. I do appreciate, however, all of the ideas put forth. Keep
them coming.

Thanks,

Ken

Best regards,
Spehro Pefhany

http://www.speff.com

 

[Spehro Pefhany]

I must confess that I am on a very tight budget here and have to use what I
have on hand. I do appreciate, however, all of the ideas put forth. Keep
them coming.

Okay, salvage an EPROM, 2716, 2732, whatever has a window so it can be
erased and is 5V only, from an old computer or whatever, borrow an
EPROM eraser and a programmer and use a hex file something like this
one to burn the EPROM, after erasure, of course:

:1000000000010203040506070809808080808080C3
:100010000A0B0C0D0E0F101112138080808080804F
:100020001415161718191A1B1C1D808080808080DB
:100030001E1F202122232425262780808080808067
:1000400028292A2B2C2D2E2F3031808080808080F3
:1000500032333435363738393A3B8080808080807F
:100060003C3D3E3F4041424344458080808080800B
:10007000464748494A4B4C4D4E4F80808080808097
:100080005051525354555657585980808080808023
:100090005A5B5C5D5E5F60616263808080808080AF
:1000A0008080808080808080808080808080808050
:1000B0008080808080808080808080808080808040
:1000C0008080808080808080808080808080808030
:1000D0008080808080808080808080808080808020
:1000E0008080808080808080808080808080808010
:1000F0008080808080808080808080808080808000
:00000001FF

Use output bits 0..6 as the binary output (0 to 0x63) and bit 7
indicates an invalid BCD input (0= okay, 1= error). Address lines 0..3
go to the LSD and address lines 4..7 go to the MSD thumbwheel. Tie the
unused address lines to Vss.


Best regards,
Spehro Pefhany

 

[K Wind]

Okay, salvage an EPROM, 2716, 2732, whatever has a window so it can be
erased and is 5V only, from an old computer or whatever, borrow an
EPROM eraser and a programmer and use a hex file something like this
one to burn the EPROM, after erasure, of course:

:1000000000010203040506070809808080808080C3
:100010000A0B0C0D0E0F101112138080808080804F
:100020001415161718191A1B1C1D808080808080DB
:100030001E1F202122232425262780808080808067
:1000400028292A2B2C2D2E2F3031808080808080F3
:1000500032333435363738393A3B8080808080807F
:100060003C3D3E3F4041424344458080808080800B
:10007000464748494A4B4C4D4E4F80808080808097
:100080005051525354555657585980808080808023
:100090005A5B5C5D5E5F60616263808080808080AF
:1000A0008080808080808080808080808080808050
:1000B0008080808080808080808080808080808040
:1000C0008080808080808080808080808080808030
:1000D0008080808080808080808080808080808020
:1000E0008080808080808080808080808080808010
:1000F0008080808080808080808080808080808000
:00000001FF

Use output bits 0..6 as the binary output (0 to 0x63) and bit 7
indicates an invalid BCD input (0= okay, 1= error). Address lines 0..3
go to the LSD and address lines 4..7 go to the MSD thumbwheel. Tie the
unused address lines to Vss.

Thanks. I'll take a look at what I have.

Ken

Best regards,
Spehro Pefhany

http://www.speff.com

 

[Tom Del Rosso]

Thanks for the info. The clock would be around 10KHz to 100KHz and
made of CMOS inverters or a 4093. The maximum number of counters
would be four each. I haven't looked at any specs on how many TTL
devices can be driven by whatever device would be used for the clock,
but will when the time comes. I will also look at what is required by
the 74193s.

Strictly speaking, those CMOS outputs can barely drive a single TTL. If
you want to use counters (rather than an EPROM) and drive them from CMOS
it would be best to use all CMOS counters, like HC190 and HC193.
Otherwise you should buffer the clock before it goes to the TTL. IOW
the clock generator would drive the CMOS counter, and also drive a CMOS
buffer, and the buffer would drive the TTL clock.