74HC Datasheet, 74HC stage Binary Counter Datasheet, buy 74HC, 74HC pdf, ic 74HC description/ordering information. The ‘HC devices are stage asynchronous binary counters, with the outputs of all stages available externally. A high. Data sheet acquired from Harris Semiconductor. SCHSD. Features. • Fully Static Operation. • Buffered Inputs. • Common Reset. • Negative.
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74HC Datasheet(PDF) – NXP Semiconductors
Yes, delete it Cancel. I’m going to ignore those timing calculations for the moment next log because there’s an even bigger problem here – it takes too long for the address to settle. Monitors can handle some clock frequency variations. All these numbers involving multiples of propagation-delays are making me question even further how I got the ol’ LCD controller running. Add in the 12 ns access time of the SRAM, and we’re definitely over budget. If I’m reading the datasheet correctly, the maximum delay from clock edge to valid outputs is In this case, it’s not memory but registers.
Synchronous Counters Synchronous counters use extra logic to form the next state from the previous one directly, without waiting for clocks to ripple through, so the datasheet settle faster. Those bounces won’t kill this project.
Maybe I’m doing this wrong? I started with the VHC part this datasgeet I can hook one to the four-channel scope and have a look at the delays between the LSB and successive bits. I have to go take them out of my shopping cart now: How about the 74HC? If I were going to build a bunch of these, I’d try harder to get the 74HC to work.
This could be interesting. In the store-each-dot-period-as-a-byte plan, this is trivial – I have full and easy control of all the singals on on a per-dot basis.
So, what the heck, I’ll look at timing before slapping something together. So, with two of them connected to generate 19 bits of address, the tpd from the eatasheet edge to the MSB settling is: Doesn’t look promising – although the typical 21ns 6V or 25ns 4.
Synchronization is an issue, but it’s worth thinking about – maybe if the PIC runs from the external Musta been a bunch datasheet pixie-dust in there, or a poor memory of 18 years ago.
The 74VHC is another candidate – it has twin 4-bit counters in a package, so three ICs would be necessary. The row address can be updated from the horizontal sync. Here’s a simplified schematic of datasheet guts of the VGA framebuffer it ignores the reset and connections between the two ”s required to generate 19 bits of address.
The dot clock is Interestingly, it also has a synchronous clear, and connections for synchronous expansion between counters with lookahead carry outputs. Interesting discovery upon looking back Maybe a fast external counter for the lowest 4 or 8 bits, and the PIC generates the upper ones? About Us Contact Hackaday.
74HC data sheet datasheet & applicatoin notes – Datasheet Archive
I need 5 of them, which sucks. Yeah, I had read about keeping video blanked outside of the active area. VHC to the rescue? Cycling back the hsync for a second counter is interesting.
74HC4040 Datasheet PDF
I’ll have to give that one some thought. This also ignores the fact that two 74HCs need to be chained to generate datahseet bit address: Surely the 74VHCwith its Mhz typical max clock frequency will do the job!
I saw the 25 MHz trick in your terminal project – good to know.
This would work – with the 12ns SRAM access time, still way under the 40ns cycle time. I’m datasheett typical values for the moment; if it doesn’t work there, it’s not going to work worst-case, either. What about using the fastest PIC available and bitbanging the address lines?
Did Xatasheet miss something on the ripple counters? I haven’t used VHC logic before, 74hv4040 keep seeing it around. It’s a shame, because the ‘ packs bits into a single package.
In the schematic above, the ‘ counters increment the address on the rising edge of the clock, while the ‘ d-flop captures the data from the last address before it changes. Don’t forget that ground-bounce! Even if you could output a new address every cycle, that’s still only about half of the