Input Configuration
For GPI configuration, you have two signal modes available: Mode "Single-ended", and mode “Differential”. Mode "Single-ended" is the default mode.
- In mode Single-ended”, you can use the GPIs on the GPIO socket for receiving up to 4 single-ended signals.
- In mode “Differential”, you can use the GPIs on the GPIO socket for receiving up to 2 differential signals.
To use the input pin pairs B1/B2 and A1/A2 on the GPIO socket for receiving differential signals, you have to switch them to “Differential” mode.
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Switching to "Differential" Mode |
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The physical interface of the GPIO is configurable. If you need another configuration of the input signals, i.e.:
you can easily configure the GPIs according to your needs. For configuration, you use a command line tool which has been installed on your system together with the Silicon Software runtime. For more information, see Input Configuration and Configuring the Physical Properties of Trigger Signals. |
You can switch between the modes "Differential" and "Single-ended" using the command line tool as described in Configuring the Physical Properties of Trigger Signals.
Single-Ended Mode (Default Mode)
In default configuration (“Single-ended” mode), all four input pins of the GPIO are configured to receive single-ended signals (in pull-up mode):
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-> 1 single-ended signal | |
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-> 1 single-ended signal | |
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-> 1 single-ended signal | |
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-> 1 single-ended signal |
Differential Mode
If you need differential input signals, you can switch the GPIs of your Front GPIO into "Differential" mode. In "Differential" mode, fourinput pins of the GPIO are configured to receive 2 differential signals:
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-> 1 differential signal (pin A1 +, pin A2 -) | |
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-> 1 differential signal (pin B1 +, pin B2 - ) |
How to switch between "Single-ended" and "Differential" mode, see Configuring the Physical Properties of Trigger Signals.
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Custom Configuration “Pull-Down” |
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Both configurations (Differential and Single-ended) can be used in pull-up and pull-down mode. Default is the pull-up mode. If you want to use the inputs in pull-down mode, you can configure the pins accordingly, see Configuring the Physical Properties of Trigger Signals. |
Electrical Characteristics of the Physical Inputs:
Electrical |
Minimum |
Typical |
Maximum |
Unit |
---|---|---|---|---|
Supply voltage | 4.5 | 28 | V | |
Input threshold | 20% Supply Voltage | |||
Differential voltage | 10 | mV |
Timing Characteristics of the Physical Inputs:
Timing |
Minimum |
Typical |
Maximum |
Unit |
---|---|---|---|---|
Propagation delay | 40 | 60 | 80 | ns |
Min. pulse width | 200 | ns | ||
Max. frequency | 2.5 | MHz |
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Board Protection |
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LightBridge 2 VCL has been designed with a varistor which opens at an input voltage of 30V (on the GPIOs) to let the onboard surge protector get active to protect the board. At a total supply voltage of 36V, the electronic chips would become defective. |