If I finish early tonight... I will see if I can find out what's wrong... BUT!! I will send you a copy of my 8 digit using only thee pins of the mirco that believe it or not looks better than multiplexing 6 screens...

 

If I finish early tonight... I will see if I can find out what's wrong... BUT!! I will send you a copy of my 8 digit using only thee pins of the mirco that believe it or not looks better than multiplexing 6 screens...

Ok sir I'm waiting, thank you

 

You do know that the outputs of the 74LS145 are OPEN COLLECTOR and require pullup resistors to function properly.

See the bottom of page 2 on the datasheet.
http://www.ti.com/lit/ds/sdls051a/sdls051a.pdf

 

But, but, but... it's being used as a sinking driver for an LED display... just like the Elektor Junior 6502 computer used a 74145 in the early 80's... are pull-ups necessary for this use case?

 

I thought that when simply lighting an LED, by itself or in a 7-segment display, the pull up resistor is not needed.

When it is needed is if the open collector output is driving logic or other active circuitry. In the latter case, the input after the open collector output is left floating and may be misinterpreted.

The LED isn’t affected as thusly. However, I’d use pull ups, based on the “better safe than sorry” principle.

 

The 74ls145 isn't supported in Proteus.. I think you need an address decoder, not a BIN to 7 seg driver.. you need a 74hc138 to select the segments..

 

What BIN to 7-segment driver? I don’t see one in the schematic.

The seven segments are output from the uP. He has a 74HC574 in place as a driver. I wonder if that part is mislabeled, as it is s flip flop?

He DOES have a 74145 BCD to decimal chip to select digits.

 

The 74LS145 is a BCD to Decimal converter... and it is designed to output nothing if the input is invalid (non BCD)... did you not read the datasheet?

 

The 74LS145 is a BCD to Decimal converter... and it is designed to output nothing if the input is invalid (non BCD)... did you not read the datasheet?

Yes, I know that.
Yes, I’m aware of the design.
Yes, I’ve read the datasheet.

 

The 74LS145 is a BCD to Decimal converter... and it is designed to output nothing if the input is invalid (non BCD)... did you not read the datasheet?

You lost me, too. What's your point, please?

The 74LS145 BCD to Decimal Decoder/Driver should make a fine driver for the common cathodes on this display.

 

What BIN to 7-segment driver? I don’t see one in the schematic.

The seven segments are output from the uP. He has a 74HC574 in place as a driver. I wonder if that part is mislabeled, as it is s flip flop?

He DOES have a 74145 BCD to decimal chip to select digits.

Typo... My point was... This is a Proteus simulation... The 74ls145 is not a supported model... He will need to use the 74HC138.. Nothing wrong with "out of the box" thinking.. It just wont simulate in Proteus...

 

You lost me, too. What's your point, please?

The 74LS145 BCD to Decimal Decoder/Driver should make a fine driver for the common cathodes on this display.

The OP said he was getting nothing on his outputs- which likely indicates he's not inputting a valid value.

 

The OP said he was getting nothing on his outputs- which likely indicates he's not inputting a valid value.

He said no outputs on the 74ls145... He wont... It isn't modelled... He can try until the cows come home..