Atmel WinCupl

Here is an example, of a HC259 adr latch, minus the field statements QL = DV & WrQ /* Follow */ # !WrQ & Qfb /* Hold */ # Qfb & DV /* Overlap */ # Reset /* Reset Forces all HI -> All OFF */ ;

This is a change-over MUX, but the key line is the overlap one, you need a MAKE-before-break MUX.

An alterative if you are not pushed for pins, is to flip the WRN using PLD resource, hard wire that to the CLK pin, and then use WR rising edge to clock std D 16V8 registers

QL.d = Update & Di # !Update & QL;

-jg

My CUPL is a little rusty so excuse any punctuation errors...

pin[2..5] = [d0..3]; pin[12..15] = [q0..3]; pin[6,7,8] = [!ce,!oe,!wr];

field din=[d0..3]; field dout=[q0..3];

enable = !CE & OE & !WR;

dout = !enable & dout /* hold latch contents by feeding output back to input */ # enable & din;

Thanks Mike and Jim for the replies, I will go off and digest this and see what happens. This is also the first time I have used the groups, thank you very much for the replies.

Paul

Mike I started off using your code, it looks more like what I am used to using.

I am not clear on the feeding back of the output to the input. This is done internal to the PAL?

I fixed an upper/lower case problem, the enable line was uppercase and pins 6,7,8 were lower. Now I am getting a 0014CB error,

"The variable used as an input was previously assigned to an output that is neither bidirectional nor feeds back into the input array."

My device is g16v8a, when I do a device independant compile it seems happier, I guess because it doesn't know the pins (input vrs output) of my device independant device.

Here is the code I am compiling now.........

pin[2..5] = [D0..3]; pin[6,7,8] = [!ce,!oe,!wr];

pin[12..15] = [Q0..3];

field din=[D0..3]; field dout=[Q0..3];

enable = !ce & oe & !wr;

dout = !enable & dout /* hold latch contents by feeding output back to input */ # enable & din;

WHAT I THINK I UNDERSTAND......... So, we are first saying pins 2, 3, 4, 5 will be known as D0, D1, D2, & D3 next we say pins 12, 13, 15, & 15 will be outputs Q0, Q1, Q2, & Q3. next, pin 6 is chip enable active low, pin 7, is output enable active low, and pin 8 is assigned write not active low. we say DIN is the data inputs D0-D3 and DOUT is Q0-Q3.

When we are active CE is low, OE is high, and WR is low.

NOW FOR THE FUN PART........ DOUT is equal to when not enabled ANDed with DOUT ORed with enabled and the data in?

NOT SURE I GET THAT ONE.......

Thanks all again for your support,

Paul K.

input */