# looking to place some sequential logic on to a programmable device!

A

#### Andrew Crook

Jan 1, 1970
0
I am looking to place some sequential logic on to a programmable device
because I need to reduce the size of the circuit and one ic would be great.

I know nothing about how to do this, but have been told I need to use a PLD.

these look expensive and to complex for what I am doing

I guess for this project I need the smallest cheapest available

most of my circuits are based upon nand gates and d type latches, I may need
to design something like a 555 for a buzzer.

could somebody suggest one and a writer for it?

many thanks for listening

Andi

F

#### Fred Bloggs

Jan 1, 1970
0
Andrew said:
I am looking to place some sequential logic on to a programmable device
because I need to reduce the size of the circuit and one ic would be great.

I know nothing about how to do this, but have been told I need to use a PLD.

these look expensive and to complex for what I am doing

I guess for this project I need the smallest cheapest available

most of my circuits are based upon nand gates and d type latches, I may need
to design something like a 555 for a buzzer.

could somebody suggest one and a writer for it?

many thanks for listening

Andi

The cheapest will be the "In-Circuit Programmable" types with a homemade
programming cable for the LPT port and using free software from the
manu's- like Altera, Xilinx, Lattice, and Cypress. Many will sell the
IC's online- something like $3-4 per copy. The downside is the minimal configuration will be something like 36 macrocells in a 44-PLCC, so you are looking at a pricey socket. The PLD are still available, but start-up costs are out of the question because they require specialized programmers executing proprietary algorithms and cost hundreds of dollars. F #### Frank Buss Jan 1, 1970 0 Andrew Crook said: I am looking to place some sequential logic on to a programmable device because I need to reduce the size of the circuit and one ic would be great. If it doesn't have to be too fast (say some 100 kHz), you can use a PIC. Take a look at the homepage of the producer for datasheets: http://www.microchip.com And try google for example for the 16f628, which is often used for small projects. A #### Andrew Crook Jan 1, 1970 0 The PLD are still available, but start-up costs are out of the question because they require specialized programmers executing proprietary algorithms and cost hundreds of dollars. i was looking at http://tutor.al-williams.com/pld-1.htm if I could draw my sequential logic circuits, mainly nand gates and d type flip-flops, in the software and write in to a cheap simple PLD (classic) that would be great. what do you think... any other ideas Andi A #### Andrew Crook Jan 1, 1970 0 for about$3 for a PIC12F675-I/P ( i cant seem to find a data sheet) chip
this is the best solution so far
a compatable writer for $99.95.. any cheaper i would like to know! my only problem would be choosing the software as i have not used this setup before! i would like a simple cheap version basic to begin with, good support and documentation Andi F #### Frank Buss Jan 1, 1970 0 Andrew Crook said: for about$3 for a PIC12F675-I/P ( i cant seem to find a data sheet)

It is all on the Microchip-site, only some clicks from start:

chip this is the best solution so far
a compatable writer for \$99.95.. any cheaper i would like to know!

There are cheaper solutions, but for example with the PICSTART Plus
you'll get the serial port pluggable writer and the software for
programming, simulation on PC and writing nearly all PICs. It's worth,
if you plan to do more with PICs in future.

F

#### Frank Buss

Jan 1, 1970
0
Frank Buss said:
It is all on the Microchip-site, only some clicks from start:

Note: I don't get money for this recommendation and there are very good
other microcontrollers from http://www.atmel.com/ and
http://www.cypress.com/ , but I've tried PICs only and don't have any
experience with other microcontrollers.

M

#### Martin Riddle

Jan 1, 1970
0
Altera would be one option then. Their interface is graphical (as well as VHDL).
The Base package, which is free, can do up to the MAX7000 series. However, Altera is pricer than
most others.
I have a schematic for their maxblaster LPT programmer, and have built my own.
email me if you need the board files to construct your own.

Cheers

P

#### Paul Burke

Jan 1, 1970
0
Andrew said:
i was looking at
http://tutor.al-williams.com/pld-1.htm

if I could draw my sequential logic circuits, mainly nand gates and d type
flip-flops, in the software and write in to a cheap simple PLD (classic)
that would be great. what do you think...

My advice is DON'T do it that way. You know what you want- otherwise you
won't be able to draw the circuit as gates and flipflops. Write out what
you want as pseudocode, for example:

when (A OR B) == 1 // Set condition
Latch 1 = 1
else when (A AND B) == 1
Latch 1 = 0 // Reset condition
else
Latch 1 = Latch 1 // Hold condition

Then get hold of a suitable software suite, I'd choose Lattice or Xilinx
but that's on;ly because I've been using them for years. Rewrite using
the appropriate syntax for the languages available (I find ABEL much
easier than VHDL, others will differ). Compile and fit. If it won't fit
in the smallest device, choose the next one up. If your logic is simple
and small it will fit.

Then buy the devices! Xilinx Coolrunner 64 logic block parts are only
about £2.50 each in small quantities, and the amount of heartbreak they
save is worth every penny. You can get them in PLCCs so prototyping is
no bother. Lattice small ones (1016E, 2032 etc) are also quite cheap.

Paul Burke

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