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You can fashion a logic detect from CMOS gates or such. Bear in mind that you have four things to detect:

• high-Z (undriven)
• static low
• static high
• changing signal

There's plenty of examples of handmade 'logic probes' that can do some or all of these things. I'll leave that up to you.

Fortunately, pre-made logic probes are widely available at reasonable cost ($10 - $30). These pen-like probes are powered by your board and indicate all four conditions: high-Z, fixed high, fixed low, and pulsing. I've used them, and in my experience they're a handy item to have for board-level troubleshooting. More here: https://www.electronics-notes.com/articles/test-methods/logic-probes/what-is-a-logic-probe.php

Moving up the food chain, you can also get USB-based logic analyzers for your PC. More about those here: https://hackaday.com/2017/07/29/everything-you-need-to-know-about-logic-probes (note: they're calling the thing a 'logic probe', but it's really a logic analyzer.) These are far less expensive than a 'scope and for some work (like I2C, SPI and other protocols) much more useful. Here's an analyzer for less than $20.

If you have a bit more budget, consider a USB-based scope. Then you can look for some basic signal issues if that's a concern (might be for 12MHz.)

Finally, how about a combo 'scope, logic analyzer, pattern generator, and power supply: https://digilent.com/shop/analog-discovery-3/

You can fashion a logic detect from CMOS gates or such. Bear in mind that you have four things to detect:

• high-Z (undriven)
• static low
• static high
• changing signal

There's plenty of examples of handmade 'logic probes' that can do some or all of these things. I'll leave that up to you and your favorite search engine.

Fortunately, pre-made logic probes are widely available at reasonable cost ($10 - $30). These pen-like probes are powered by your board and indicate all four conditions: high-Z, fixed high, fixed low, and pulsing. I've used them, and in my experience they're a handy item to have for board-level troubleshooting. More here: https://www.electronics-notes.com/articles/test-methods/logic-probes/what-is-a-logic-probe.php

Moving up the food chain, you can also get USB-based logic analyzers for your PC. More about those here: https://hackaday.com/2017/07/29/everything-you-need-to-know-about-logic-probes (note: they're calling the thing a 'logic probe', but it's really a logic analyzer.) These are far less expensive than a 'scope and for some work (like I2C, SPI and other protocols) much more useful. Here's an analyzer for less than $20.

If you have a bit more budget, consider a USB-based scope. Then you can look for some basic signal issues if that's a concern (might be for 12MHz.)

Finally, how about a combo 'scope, logic analyzer, pattern generator, and power supply: https://digilent.com/shop/analog-discovery-3/

Logic probes are a low-cost way of sensing the state of a signal. These are pen-like probes powered by your board, that indicate fixed high, fixed low, and pulsing. Widely available, they sell for $10 - $30. I've used them, and in my experience they're a handy item to have for troubleshooting. More here: https://www.electronics-notes.com/articles/test-methods/logic-probes/what-is-a-logic-probe.php

You can also get USB-based logic analyzers for your PC. More about those here: https://hackaday.com/2017/07/29/everything-you-need-to-know-about-logic-probes (note: they're calling the thing a 'logic probe', but it's really a logic analyzer.) These are far less expensive than a 'scope and for some work (like I2C, SPI and other protocols) much more useful. Here's an analyzer for less than $20.

If you have a bit more budget, consider a USB-based scope. Then you can look for some basic signal issues if that's a concern (might be for 12MHz.)

Finally, how about a combo 'scope, logic analyzer, pattern generator, and power supply: https://digilent.com/shop/analog-discovery-3/

You can fashion a logic detect from CMOS gates or such. Bear in mind that you have four things to detect:

• high-Z (undriven)
• static low
• static high
• changing signal

There's plenty of examples of handmade 'logic probes' that can do some or all of these things. I'll leave that up to you.

Fortunately, pre-made logic probes are widely available at reasonable cost ($10 - $30). These pen-like probes are powered by your board and indicate all four conditions: high-Z, fixed high, fixed low, and pulsing. I've used them, and in my experience they're a handy item to have for board-level troubleshooting. More here: https://www.electronics-notes.com/articles/test-methods/logic-probes/what-is-a-logic-probe.php

Moving up the food chain, you can also get USB-based logic analyzers for your PC. More about those here: https://hackaday.com/2017/07/29/everything-you-need-to-know-about-logic-probes (note: they're calling the thing a 'logic probe', but it's really a logic analyzer.) These are far less expensive than a 'scope and for some work (like I2C, SPI and other protocols) much more useful. Here's an analyzer for less than $20.

If you have a bit more budget, consider a USB-based scope. Then you can look for some basic signal issues if that's a concern (might be for 12MHz.)

Finally, how about a combo 'scope, logic analyzer, pattern generator, and power supply: https://digilent.com/shop/analog-discovery-3/

Logic probes are a low-cost way of sensing the state of a signal. These will usually indicate high, low, and pulsing. About $10 - $30, they're a handy item to have for troubleshooting. Widely available. More here: https://www.electronics-notes.com/articles/test-methods/logic-probes/what-is-a-logic-probe.php

You can also get USB-based logic analyzers for your PC. More about those here: https://hackaday.com/2017/07/29/everything-you-need-to-know-about-logic-probes (note: they call the thing a 'logic probe', but it's really a logic analyzer.) These are far less expensive than a 'scope and for some work much more useful.

Logic probes are a low-cost way of sensing the state of a signal. These are pen-like probes powered by your board, that indicate fixed high, fixed low, and pulsing. Widely available, they sell for $10 - $30. I've used them, and in my experience they're a handy item to have for troubleshooting. More here: https://www.electronics-notes.com/articles/test-methods/logic-probes/what-is-a-logic-probe.php

You can also get USB-based logic analyzers for your PC. More about those here: https://hackaday.com/2017/07/29/everything-you-need-to-know-about-logic-probes (note: they're calling the thing a 'logic probe', but it's really a logic analyzer.) These are far less expensive than a 'scope and for some work (like I2C, SPI and other protocols) much more useful. Here's an analyzer for less than $20.

If you have a bit more budget, consider a USB-based scope. Then you can look for some basic signal issues if that's a concern (might be for 12MHz.)

Finally, how about a combo 'scope, logic analyzer, pattern generator, and power supply: https://digilent.com/shop/analog-discovery-3/