Cable tester

[Rich Webb]

Hi,

I am designing a multicore (19 cores) cable tester, I need 19 outputs routed
back into 19 inputs. I was going to use a PIC (16F877) connected to 2 x 8255
multi i/o chips to give me 19 outputs and 19 inputs.

Has anybody got any ideas on a better way of doing this as the 8255 chip is
outdated.

Can anybody give me the numbers of other multi i/o chips that are up-to-date
or have more i/o lines.

Any help will be appreciated.

One bidirectional 8-bit port and a small CPLD. Five bits to address the
input and output pins, one bit address latch, one bit for direction
(read or write), and one data bit.

If write is asserted then on the active edge of the latch the data value
is written to the selected output pin. If read is asserted, latch grabs
the value of the selected input pin and presents it on the data pin.

At a minimum it looks like you'd need 46 I/O pins. A 64 macrocell
CY37064 should do the trick for less than $10 (qty 1). About the same
cost as two 8255s and probably easier to interface.

 

[Ian Helie]

Hi,

I am designing a multicore (19 cores) cable tester, I need 19 outputs routed
back into 19 inputs. I was going to use a PIC (16F877) connected to 2 x 8255
multi i/o chips to give me 19 outputs and 19 inputs.

Has anybody got any ideas on a better way of doing this as the 8255 chip is
outdated.

Can anybody give me the numbers of other multi i/o chips that are up-to-date
or have more i/o lines.

Any help will be appreciated.

Yours Hopefully,

Ian Helie.
GM7VHQ

 

[petrus bitbyter]

Hi,

I am designing a multicore (19 cores) cable tester, I need 19 outputs routed
back into 19 inputs. I was going to use a PIC (16F877) connected to 2 x 8255
multi i/o chips to give me 19 outputs and 19 inputs.

Has anybody got any ideas on a better way of doing this as the 8255 chip is
outdated.

Can anybody give me the numbers of other multi i/o chips that are up-to-date
or have more i/o lines.

Any help will be appreciated.

Yours Hopefully,

Ian Helie.
GM7VHQ

I'm not aware of any newer general purpose parallel I/O chips. These days
you either find a micro that has enough I/O lines of itself or use a PLD
that has. If it is a one of a kind projest I advise to use simple
oldfashioned 245 and 374 chips. Otherwise you can consider to use two PICs.

petrus bitbyter

 

[Spehro Pefhany]

Hi,

I am designing a multicore (19 cores) cable tester, I need 19 outputs routed
back into 19 inputs. I was going to use a PIC (16F877) connected to 2 x 8255
multi i/o chips to give me 19 outputs and 19 inputs.

Has anybody got any ideas on a better way of doing this as the 8255 chip is
outdated.

Can anybody give me the numbers of other multi i/o chips that are up-to-date
or have more i/o lines.

How about half a dozen HC4051s and scan away? Cheap n' cheerful.

Best regards,
Spehro Pefhany

 

[Jens Gydesen]

Hi,

I suggest you use serial components, e. g. 3 pcs 74HC595 to set the outputs,
and 3 pcs 74HC597 to read back.

Very simple and low cost.

Regards

Jens