figure and Table 1:The AUX I/O connector has two nodes that control this port:
Instrument: Controls the general operating mode of the AUX I/O that applies to all of the AUX I/O signals.
Signal IO: Defines which specific signals are going to be input/output on the AUX I/O port. These are specific to your application and to the type of Signal Studio software used.
This topic covers the use case for the AUX input signals and has the following sections (For more information—including AUX external signals—refer to Using the Keysight X-Series Signal Generator AUX I/O Port or and to AUX I/O Input/Output Pin-outs and Signals figure and Table 1:
The AUX input signals can be used to provide feedback to the real-time signal generation software, such as N7602B Signal Studio for real-time GSM-EDGE signals.
For the N7602B operation, AUX input signaling can be used to provide a trigger to toggle between "Primary Frame" and "Secondary Frame" modes. An external signal is connected to the AUX input port and is used to control the secondary frame.
The AUX input port can be configured in the Signal IO node of the N7602B software. Refer to Figure 1.
The AUX port has a “Multiplexed” mode and a “Dedicated” mode. Figure 2 indicates that the AUX I/O port is set to “Multiplexed” mode. In Figure 1, notice the parameter area, where the AUX5 pin is selected. This means that the GSM-EDGE real-time system will expect you to supply a secondary frame trigger feedback signal using the AUX5 pin of the AUX I/O connector.
The Aux connector can also be used as real-time data input. Because of speed limitations, the real-time data inputs can only be used in “Multiplexed” mode.
This section describes the Signal IO node as it relates to the AUX I/O port input signals. The following AUX port settings are displayed in Figure 1. For more information, refer to Signal IO or to the MXG/EXG's User Guide (p/n: N5180-90056).
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State |
On or Off — Off means the AUX signaling is ignored |
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Data Polarity |
Positive or Negative — Positive means a 3.3-volt signal is interpreted as a ‘1’ and a 0-volt signal is a ‘0’. Negative selection inverts this so that a 3.3-volt signal is interpreted as ‘0’ and 0-volt signal is interpreted as ‘1’. |
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In the Instrument node, the > can be selected as “Multiplexed” or “Dedicated” – in this case it is selected as “Multiplexed”. Refer to Figure 2. |
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First Address |
For the MXG/EXG it is not necessary to select any Group addresses, so these can be left in their default state. |
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Second Address |
For the MXG/EXG it is not necessary to select any Group addresses, so these can be left in their default state. |
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Aux Port Pin |
Because the AUX port mode is selected as “Multiplexed” these settings are not active, and are shown in grey text. When “Dedicated” mode is selected, this field is used to select the AUX pin of the dedicated connection. |
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Baud Rate |
Because the AUX port mode is selected as “Multiplexed” these settings are not active, and are shown in grey text. When “Dedicated” mode is selected, this field is used to select the baud rate of the dedicated connection. |
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AUX Pin/Bit Select |
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Secondary Frame Trigger |
This enables you to select which AUX pin (AUX0 ... AUX11) will be routed to control the N7602B secondary frame trigger. |
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Real-Time Data Input Pin 1 |
Selects an AUX pin (AUX0 ... AUX11) for the real-time data input when using multiplexed mode. |
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Real-Time Data Input Pin 2 |
Selects an AUX pin (AUX0 ... AUX11) for the real-time data input when using multiplexed mode. |
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Real-Time Data Input Pin 3 |
Selects an AUX pin (AUX0 ... AUX11) for the real-time data input when using multiplexed mode. |
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Real-Time Data Input Baud Rate |
Selects a baud rate for the real-time data input when using multiplexed mode. |
The AUX port has a “Multiplexed” mode and a “Dedicated” mode. In “Multiplexed” mode, auxiliary signaling is sent using level-sensitive binary signaling (3.3V LV TTL) connected to one or more AUX port input bits. In “Dedicated” mode, auxiliary signaling is sent using an RS232C like serial signal at a specified baud rate to a selected AUX port input bit.
The AUX port mode can be selected in the Instrument node's > parameter (See Figure 2), by sending a SCPI command, or by using the instrument's front panel. Refer to the MXG/EXG's User Guide (p/n: N5180-90056).
In the node there are four AUX Port Global controls.
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Operating Mode |
Select “Multiplexed” or “Dedicated". These functions are described in Signal IO Node AUX Input Parameters. |
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Input Strobe |
There are two selections: Free Run or User. In Free Run mode, the instrument samples the values of the AUX input signals (AUX0 ... AUX11), according to the instruments internal timing – this happens at about 3.5 MHz. In User mode, you must supply a strobe signal which causes the AUX input signals to be sampled. |
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Input Strobe Polarity |
You can choose Positive or Negative polarity. With positive polarity, the AUX input signals are sampled via the rising edge (0V to 3.3V transition) of a pulse (AUX strobe) supplied by you to the AUX I/O connector pin 6. With a negative polarity the AUX input signals are sampled on the falling edge of AUX strobe. |
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Output Strobe Polarity |
Determines when the AUX input signals have been sampled by looking at the AUX sample clock (connector pin 29) signal. If the Output Strobe Polarity is positive, this will be a positive going pulse (about 200 ns pulse width), which is triggered when the AUX input signals are sampled. If the polarity is negative, the AUX sample clock will be a series of negative going pulses about 200 ns pulse width. |
The Auxiliary I/O port is designed to support your real-time signal generation software configuration with the instrument, and to interface with different configurations of external equipment under test.
For example, consider a sample configuration where you are using GSM-EDGE signal generation software to control the instrument. The N7602B software can be configured to accept a trigger on the rising or falling edge of the secondary frame—from your external equipment—to toggle the frame type.
Auxiliary signaling can be delivered from external equipment in one of two formats.
A low-voltage, TTL format where, your equipment uses a binary signal connected to the AUX port in an LV TTL format with 0-volts representing a ‘0’, 3.3-volts representing a ‘1’.
If this signal cannot be delivered directly from the external equipment, an inexpensive interface board can be used to connect to external equipment with a USB connection, for example the USB Bit Whacker (SKU: DEV-00762, www.sparkfun.com), can be used to interface from your external equipment with a USB connection to the Keysight Auxiliary I/O port.
A serial format where, your equipment uses a serial-port connection, with an LV TTL RS-232 type protocol. Baud rates from 9600 to 460800 are supported in this format. For this purpose, a device can use any low voltage transistor to transistor logic (LV TTL) line that can generate RS-232 type signals, or some simple USB to RS-232 TTL signaling devices can be used.
The default serial format Positive is illustrated Figures 3 and 4 . Each signaling transmission consists of an 8-bit character (bits b7 b6 b5 b4 b3 b2 b1 b0, b0 is least-significant bit, b7 is most significant bit). The signaling transmission consists of a start bit ‘0’, followed by the 8 data bits (transmitted LSB first) followed by a stop bit ‘1’. The bit rate can be one of 9600, 19200, 38400, 57600, 115200, 230400, or 460800 bits per second.
If the polarity is selected as Negative (inverted), then the expected signal will be the inverted form shown in Figure 5.
Figure 3. Serial Data Transmission Format–Polarity is Positive (Default)
Figure 4. Polarity is Positive - Hex Example
Figure 5. Serial Data Transmission Format–Polarity is Inverted
Let us again consider the GSM-EDGE secondary frame trigger example in AUX I/O Port: Input Signaling. In this example, the external user equipment required is framed data format and a two frame structure. In Signal Studio, “Secondary Frame State” is on, and “Primary Frame” and “Secondary Frame” are visible.
The external device provides a signal to toggle the “Primary Frame” and “Secondary Frame”.
Figure 6 shows a typical interconnect diagram with a GSM device for the “Secondary frame” use case. In this example, the MXG-B RF signal is connected to the input of the customer device, and a secondary frame trigger feedback signal connected to the AUX port of the instrument.
Figure. 3 GSM-EDGE Secondary Frame Testing Example
In this case, a single binary signal could be used, and default polarity is positive, which means a rising edge of a secondary frame trigger is used to toggle the frame type. Your external equipment generates an LV TTL signal for each frame. For this configuration, the equipment connection to the MXG-B can be as simple as a cable with a single signal wire and a ground connection. For example: connecting the LV TTL signal to pin 5 of the AUX port connector, and ground to pin 13.
The single line's signaling format can be selected as Multiplexed or Dedicated. The instrument's interface enables selection of the signaling format by pressing the following keys:
> > > > > or
In the case of mode, the external equipment can send a 3.3-volt signal or 0-volt signal with each frame to communicate a command to increase or decrease power in the next frame.
In the case of mode, the external equipment can send a single character each frame to indicate a command to increase or decrease power in the next frame. Any one of these 8-bits, can be used to control the power level in the next frame. In Dedicated mode, your external equipment sends one serial character for each frame.
The instrument's AUX pins AUX0 to AUX11 are available for delivering auxiliary commands from 1- to 12-bits in width in Multiplexed mode.
In Dedicated mode, where serial format signaling is used, serial signaling can be connected to any one of the pins AUX0 to AUX11.
In Dedicated mode, all signaling is delivered in the serial format as described in AUX I/O Port: Input Signaling. Serial command signals can be connected to the AUX0 to AUX11 pins of the AUX I/O connector. The serial format transmits 8-bits at a time to the instrument. These bits can be mapped to the auxiliary signaling functions of the Signal Studio's real-time signal generation software.
In Multiplexed mode, auxiliary commands are delivered as 1- to 12-bit wide commands in LV TTL format.
Keysight X-Series Signal Generator's User Guide (p/n: n5180-90056)
