Parallel in-Serial out shift register problem

[siyom]

Below is my simulation for a digital signal generator.The timer and everything else is working but the problem begins with register,i want the register to serially output the following sequence: 01011101 and from my understanding that has to be done by tying the relevant inputs to either 0V or 5V,and i've done that but my simulation is still not working,the period from the 555 timer is 10 seconds,thanks in advance[img]http//untilted[/img][attachment=0]

This is the picture of the circuit I'm talking about

untitled.GIF (7.86 KiB) Viewed 7534 times

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This is the picture of the circuit I'm talking about

untitled.GIF (7.86 KiB) Viewed 7534 times

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[Major_Problem]

Could be that the preset value is loaded at a transition of the SH/LD input. And once it has shifted, you need to preset again. But I have to check the datasheet to be sure.

Greetz,
Wim

[Major_Problem]

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Part of datasheet HC166.

HC166.jpg (110.28 KiB) Viewed 7397 times

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How I read the datasheet is as follows:

The data (parallel inputs A to H, D0 to D7) are read at ~SH/LD (Shift/Load) low and INH (CE) transitioning from low to high.
So data has to be stable at the rising flank of INH. Following this: Nothing will hapen until you take INH down to zero again.
After the data is presented at QH (Q7), the register inside is empty so you have to do the same sequence again.
Perhaps programmin a PIC processor is easyer than using logic buildingblocks.

Please post back.
Greetz, Wim

[siyom]

Using a microcontroller is far easier than having to use timers which are very unrealiable,i would have used microcontrollers if i had the choice but the design specs forbid me from using them and i have resorted to just using a 4017 counter instead