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Product data sheet. 1 General description. The 74HC; 74HCT decodes three binary weighted address inputs. (A0, A1 and A2) to eight. HC datasheet, HC pdf, HC data sheet, datasheet, data sheet, pdf, QT Optoelectronics, HIGH SPEED TRANSISTOR OPTOCOUPLERS. HC 1-of-8 Decoder/demultiplexer. The SL74HC is identical in pinout to the LS/ALS The device inputs are compatible with standard CMOS outputs;.

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Haven’t received registration validation E-mail? User Control Panel Log out. Forums Posts Latest Posts. Forum Themes Elegant Mobile. Essentials Only Full Version. MCP – Odd results? I’m going wrong somewhere but there has to be a limit to how many times I can read the datasheet before mental atrophy sets in!

CS is driven through a HC decoder. This is the scenario: I then read SDO to see if a conversion is ready.

MCP3551 – Odd results?

If it is, I clock the result out. If not, I set CS high and do other stuff until dataheet next time, assuming that polling CS either does nothing if in the middle of a conversion or initiates a new conversion. I get odd results. I cannot see anywhere where I have broken any rules. However, I notice in trawling for source code, that datzsheet example from Microchip applies a 1ms low-going pulse to the CS.


Is this a clue? Also, I see in one app note schematic, a 1K resistor in each digital line.

Could a tiny bit of ringing on the line upset the device? This is really proving problematic. Until I crack this, I’m stymied. Any help gratefully received. Please bear in mind that I have been tinkering with the code for several days and have tried many variations. Changing the address pins with the enables strapped active is likely to cause glitches.

HC Datasheet PDF – System Logic Semiconductor

Hey – that’s an interesting thought. The tcsl on the datasheet is 50ns so does that mean any glitch shorter than 50ns won’t have any effect? I take your point about the but there is one bit of exculpatory evidence: The transitions from Y0 being active to Yn being active datahseet any glitches ought to appear on the other outputs.

Moreover, even if there is a splurge on the falling edge, it shouldn’t have any further datasheett Meanwhile, thanks for your suggestion.

I’m off glitch hunting. It’s bound to be some devilish little detail confounding me. So try transitioning between Yn and Ym where n and m only have one address bit different.


That should be glitch free and will do for testing.

This is a best guess: What language is your source in? By coincidence, I am transitioning with one bit change only.

I have made some progress.

It does seem to require a 1ms start pulse. I don’t know why this should be. Maybe it’s a footnote in the datasheet. Therefore, it needs to be. And so seems to be the case. It seems unlikely but it would explain the random nature of the results.

Thanks again for your help! I’m now back to the first code but with a small adjustment. The waveforms are perfect. It must be in the datasheet. Microchip are usually pretty thorough. But I’ve read it and read it and I cannot datasheeet anything that would tell me. Thanks for your help.

HC138 Datasheet

Sometimes a conversation with someone knowledgeable just frees up the brain a bit! Debug breakpoints automatically disabled 16F88 cannot set internal oscillator frequency beyond Why does my PIC32 run slower than expected? M Super Member Total Posts: