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A control on the logic probe allows either the capture and storage of a single event or continuous running. When the logic probe is either connected to an invalid logic level (a fault condition or a tri-stated output) or not connected at all, none of the LEDs light up. Another control on the logic probe allow selection of either TTL or CMOS ...
Logic analyzer. A logic analyzer is an electronic instrument that captures and displays multiple logic signals from a digital system or digital circuit. A logic analyzer may convert the captured data into timing diagrams, protocol decodes, state machine traces, opcodes, or may correlate opcodes with source-level software. Logic analyzers have ...
The following basic logic symbols shall be used. [9] AND: A condition in which all preceding or succeeding paths are required. The symbol may contain a single input with multiple outputs or multiple inputs with a single output, but not multiple inputs and outputs combined (Figure 5).
The NOT gate outputs a zero when given a one, and a one when given a zero. Hence, it inverts its inputs. Colloquially, this inversion of bits is called "flipping" bits. [1] As with all binary logic gates, other pairs of symbols — such as true and false, or high and low — may be used in lieu of one and zero.
To provide the boundary scan capability, IC vendors add additional logic to each of their devices, including scan cells for each of the external traces. These cells are then connected together to form the external boundary scan shift register (BSR), and combined with JTAG Test Access Port (TAP) controller support comprising four (or sometimes more) additional pins plus control circuitry.
The result is a frequency compensated probe for modest frequencies. It presents a load of about 10 megohms shunted by 12 pF. Such a probe is an improvement, but does not work well when the time scale shrinks to several cable transit times or less (transit time is typically 5 ns).
JTAG (named after the Joint Test Action Group which codified it) is an industry standard for verifying designs of and testing printed circuit boards after manufacture.. JTAG implements standards for on-chip instrumentation in electronic design automation (EDA) as a complementary tool to digital simulation. [1]
Dynamic logic has a few potential problems that static logic does not. For example, if the clock speed is too slow, the output will decay too quickly to be of use. Also, the output is only valid for part of each clock cycle, so the device connected to it must sample it synchronously when it is valid.