4. Page 6 Over the pandemic, many people have been taking lateral flow tests (LFTS). The LFT detects a COVID-19 antigen when a person is infected with COVID-19. A person's sample may be placed on the LFT and after 30 minutes the result of the test can be read. If the test is valid then a coloured bar should be seen in the display window at the area indicated by "C". If the area designated T has a coloured bar, then antigen has been detected. However, a test should only be considered positive if a bar is present at both Cand T. Consider you are designing an electronic LFT test device. The electronic LFT device has the addition of 8 detectors spread across the length of the display window to detect the presence of the coloured bars. The 8 detectors (i.e. ranges) are designated to output a linear 3-bit digital code of the form ABC when any bar is seen in that range. Due to the chemical diffusion process, the two bars, C and T. are not guaranteed to be present at an exact location, therefore it has been decided to allow for the detection of each bar within a valid range. The valid ranges are defined in table 1: Table 1. electronic LFT detector Range с (ABC) 000 001 antigen detected 010 antigen detected 011 Test valid Test valid 110 111 100 101 Considering table 1, it can be deduced that • a test is valid (C-1) if ranges 100 or 101 are detected. C=0 otherwise. • antigen is detected (T=1) if ranges 001 or 010 are detected. T=0 . a test should only be deemed positive if both C=1 AND T=1. BI1EE17 2021/2 A 800 otherwise, Page 7 Given the 3-bit code ABC from table 1, your task is to: a) use a k-map (given in Figure 1 for reference), to find the minimized logic expression for signal C. TR marks
Given the 3-bit code ABC from table 1, your task is to: a) use a k-map (given in Figure 1 for reference), to find the minimized logic expression for signal C, [8 marks] b) use a k-map (given in Figure 1 for reference), to find the minimized logic expression for signal T, [8 marks] c) Define the logic to output a positive infected signal indication, [2 marks] d) Define the logic to output a negative infected signal indication. [2 marks] Figure Q4-1: 3-input k-map for reference B 0 40 B1 11 B0
4. Page 6 Over the pandemic, many people have been taking lateral flow tests (LFTS). The LFT detects a COVID-19 antigen
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4. Page 6 Over the pandemic, many people have been taking lateral flow tests (LFTS). The LFT detects a COVID-19 antigen
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