Clocks

The Micro1401-3 has five clocks, used for timing external signals (clocks 0 and 1), generating general purpose timing pulses (clock 2), controlling waveform output (clocks 3 and 4) and controlling the waveform input sampling rate (clock 4).

Micro1401 Clocks

These clocks are managed automatically by the application software. The user may often need to drive a clock from an experiment, for example to trigger the start of sweeps of waveform sampling. The BNC Trigger input on the front panel will be connected to the correct clock by software, to act upon your signal.

Sometimes, you need pulses generated by the application software to drive your experiment. The BNC Clocks connector brings the output of clock 2 to the front panel. Your application manual will describe this, if it is relevant.

You may need to take your timing source from outside the Micro1401, instead of the internal crystal clock. All the clocks can be programmed to use an external frequency source on pin 7 on the back panel Cannon 15 pole socket marked Events, in place of the internal sources.

Where signals are to be timed or counted, the application program may use the front panel Event 0 and 1 inputs. For more than two signals, the rear panel Digital inputs, or special purpose top boxes, may be used.

Technical details

The inputs respond to TTL or switch closure signals, and are held internally to +5 Volts by 10 kOhm resistors. Input pulses should not be less than 100 ns wide and must fall below 0.8 Volts to guarantee recognition. To pull the inputs low, the driving device must be able to sink at least 0.5 mA. The safe working range of the BNC inputs is up to ±10 Volts.


Clock E inputs

More clock-related inputs, the Clock E series, are provided on the rear panel Events connector. These inputs provide close control of the clocks for people writing their own software. Full details are given in the 1401 family programming manual, and the Micro1401 technical manual. The front panel Event inputs 0 and 1 are often assigned by software to the Clock E0 and E1 inputs.

Micro1401 Clock E inputs
Technical details

The F input, pin 7 on the rear Events connector, responds to TTL or switch closure signals, and is held internally to +3 Volts. The input clock rate should not be greater than 10 MHz; no pulse should be narrower than 50 nanoseconds.

The Clock E inputs respond to TTL or switch closure signals, and are held internally to +5 Volts by 10 kOhm resistors. Input pulses should not be less than 100 ns wide and must fall below 0.8 Volts to guarantee recognition. To pull the inputs low, the driving device must be able to sink at least 0.5 mA.

The safe working range of these inputs is 0 to +5 Volts.

The sense of the Clock E and ADC external convert inputs may be inverted by a switch option, but the inputs would all then be held active high if no input is connected.

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