Embedded Systems Design Europe - June/July 2008 - (Page 29)

debugging setup conﬁguration. At the – which intuitively may appear timebase setting selected (20 to be excessively long – the probns/div), the default conﬁguraability of capturing the glitch tion minimized acquisition within 5 seconds was actually memory while maximizing very high, as determined in the waveform update rate. following probability calculation: Using the default realtime sampling mode, two P(5s) = 100 x (1 – [1-(100/s x digital signals were probed 200ns)](95,000/s x 5s)) using two analog acquisition = 99.9925% channels, while also probing ﬁve time-correlated digital The probability of reliably signals using the MSOs’ capturing this same metastable logic channels. No parametric and jitter on an MSO with a measurements or waveform lower update rate would be math functions were turned Fig 2: An Agilent MSO7104A quickly captures the extremely low. In certain cases infrequent metastable state on channel 1 while on. This step helps to maxiMSOs will tradeoff waveform also using logic channels. mize update rates on most update rate performance when scopes. using logic channels of acquisiThe signal used as the trigger tion. Waveform update rates of just 125 = 98.1% source (rising edge of the channelwaveforms per second have been meaEven though the dead-time percent1 input) included signiﬁcant jitter sured in some situations when using logage of this MSO was approximately on the falling edge along with an ic channels, speciﬁcally when using other 98% with the timebase set at 20 ns/div infrequent metastable state (glitch) coincident with the rising edge of the signal. The infrequent glitch occurred approximately 100 times per second on average. To determine the probability of capturing the XC2200 glitch, 5 seconds was assumed as a ARM7/9/11 TriCore MPC55xx reasonable observation time for the calculations. Figure 2 shows that the MSO reliably captured the random and infrequent metastable state (glitch) on channel 1 while also capturing several digital signals using the ED S PE H logic input channels of this MSO. H IG ST BU With a measured waveform update RO LE rate of approximately 95,000 waveXIB F LE forms per second and a 5-second observation time, the MSO easily showed this infrequent anomaly at the center-screen trigger point, along with jitter on the falling edge of the signal. With an acquisition display window of 200 ns (20 ns/div x 10 divisions), and an acquisition cycle time of 10.5 µs (1/95,000 waveforms/sec), dead-time percentage of this measurement was determined to be: % DT = 100 x (1- (95,000/s x 200ns)) www.embedded.com/europe | embedded systems design europe | JUNE – JULY 2008 29 http://www.pls-mc.com http://www.pls-mc.com http://www.embedded.com/europe

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Embedded Systems Design Europe - June 2008 Contents Work in Progress to Define Compact PCI Plus Power.org Demonstrates New Tools Project Supports Multi-core System Programming Altium Links Electronic to Mechanical Design PLDs Look to Cut Power Budget and Costs Project to Provide Coverage Analysis Tool Microsoft Details Windows Embedded Update Cover Feature: Leveraging Virtual Hardware Platforms for Software Allocating Memory in MATLAB-to-C Code MDD & IDEs: Making the Twain Meet in Embedded System Designs Debugging Mixed Signal Designs for Infrequent & Random Events Why Open Source is the Natural Choice for High-security Systems Bringing the Benefits of Low Power CPUs to Modular Design New Products Advertising Contacts

Embedded Systems Design Europe - June/July 2008

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