3.2 Pedestrian Crossing Button¶

Overview¶

When pedestrians cross the street, they just need to touch the button on the lamppost of the roadside signal lamp, and the green light above the traffic lane will turn into red then pedestrians can pass safely. Thus, the hard situation of citizens crossing the street is comprehensively resolved. At the same time, when there is no pedestrian to press, the light above the lane that is set for vehicles to pass will always be green, thus greatly improving the use efficiency of the road and traffic capacity.

Components Required¶

Fritzing Circuit¶

In this example, 74hc595, 7-Segment, LED, touch sensor are to be connected according to the chart.

Schematic Diagram¶

Code¶

Note

You can open the file 3.2_pedestrianCrossingButton.ino under the path of sunfounder_vincent_kit_for_arduino\code\3.2_pedestrianCrossingButton directly.

Example Explanation¶

The workflow of the project is as shown in the flow chart. The function of number display of 7-Segment is realized by writing 8 bit data into 74HC595. When there is a need of displaying「0」, the pins abcdef of the segment display will be connected to the high level. The pins, g and dp need to be connected to low level to write「0x3f」(B00111111) in the codes. The complete codes for number display of 7-Segment are as follows.

Numbers	Common Cathode
	(DP)GFEDCBA	Hex Code
0	00111111	0x3f
1	00000110	0x06
2	01011011	0x5b
3	01001111	0x4f
4	01100110	0x66
5	01101101	0x6d
6	01111101	0x7d
7	00000111	0x07
8	01111111	0x7f
9	01101111	0x6f