UPC EETAC Bachelor's Degree in Telecommunications Systems and in Network Engineering EEL

Chapter 1 problems

      - D1.10 -

Parking occupancy (32-bit ones counter)

Problems

D1.9

D1.11

1. Specifications

Counting occupied parking slots (32-bit ones counter). This project aims to represent in 7-segment displays the number of occupied parking slots. Each slot has installed an ultrasonic presence sensor which gives a €˜1€™ when occupied. Thus, the first idea here for planning the entity Parking_occupancy in Fig. 1 is to consider components such as Ones_counter_32bit where for example an input vector such as D = €œ1001 0011 1110 1111 1000 1111 1010 1110€ will produce an output K = (010101)2 = (21)10 ; a Converter_bin_BCD_6bit where for example an input such as K = (010101)2 will generate and output T = €œ0010€, U = €œ0001€ ; and a pair of HEX_7seg_decoder to drive the 7-segment displays.

Parking occupancy

Fig. 1. Symbol for the parking occupancy monitor to calculate the number of occupied parking slots. In this example it is represented the number 21 in BCD, meaning this number of detected cars in any position in the parking. VCC = 5 V.

Specifications include: symbol, truth table, data range, example timing diagram, etc.

Invent and explain the internal architecture of the Parking_occupancy circuit based on plan C2. How many VHDL files will include this project?

The HEX_7seg_decoder has active-low outputs to drive a common-anode display and its technology is LS-TTL with the characteristics represented in Fig. 2 tables. Calculate the value of the limiting resistor R1 in the worst-case scenario if each segment must be biased with 15 mA when lighting.

TTL-LS characteristics
Fig. 2. TTL-LS characteristics.

The Converter_bin_BCD_6bit is used to translate 6-bit radix-2 numbers to 2 BCD digits. Assuming the circuit is based on equations PoS (plan A) and implemented in LS-TTL technology where each gate has propagation delays as indicated in the table, calculate the maximum speed of computing.

Develop and test the circuit for a target chip Cyclone IV EP4CE115F29C7. How fast is the circuit calculating?