I started with the main control hardware which is the Raspberry Pi. The assumption here is that you already have a Raspberry Pi with the OS on it and have some Python coding experience. The Raspberry Pi controls the OPS241-A radar sensor and takes in the reported speed information. This is then converted to be displayed on the large LED 7-segment display.
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a. I want to place all electrical components other than the radar sensor and LED displays onto a single enclosed electronics PCB board mounted to the backside of the display board. This keeps the board out of sight and safe from the elements. In this manner, only two cables need to run from the back of the board to the front. One cable is the USB cable that powers the OPS241-A module and receives the measured speed data. The second cable is drives the 7-Segment display.
b. The PCB board needs to allow plenty of room for the Raspberry Pi, which takes up most of the area. I also need to make sure that I will be able to easily access several of its ports once mounted. The ports I need to access are the USB port (OPS241-A module speed data), Ethernet port (PC interface for developing/debugging Python code), HDMI port (display Raspberry Pi window and debug/development), and the micro USB port (5V power for Raspberry Pi).
c. To provide access for these ports, holes are cut in the enclosure which match the port locations on the Raspberry Pi.
d. Next I need to find room for the bread board that contains the discrete electronics components to drive the display LEDs. This is the second largest item. There needs to be enough space around it that I can jumper wires to it from the Raspberry Pi and output signals to a header for driving the LEDs. Ideally, if I had more time, I would solder the components and wires directly to the PCB board instead of using a breadboard, but for my purposes its good enough.
I started with the main control hardware which is the Raspberry Pi. The assumption here is that you already have a Raspberry Pi with the OS on it and have some Python coding experience. The Raspberry Pi controls the OPS241-A radar sensor and takes in the reported speed information. This is then converted to be displayed on the large LED 7-segment display.
a. I want to place all electrical components other than the radar sensor and LED displays onto a single enclosed electronics PCB board mounted to the backside of the display board. This keeps the board out of sight and safe from the elements. In this manner, only two cables need to run from the back of the board to the front. One cable is the USB cable that powers the OPS241-A module and receives the measured speed data. The second cable is drives the 7-Segment display.
b. The PCB board needs to allow plenty of room for the Raspberry Pi, which takes up most of the area. I also need to make sure that I will be able to easily access several of its ports once mounted. The ports I need to access are the USB port (OPS241-A module speed data), Ethernet port (PC interface for developing/debugging Python code), HDMI port (display Raspberry Pi window and debug/development), and the micro USB port (5V power for Raspberry Pi).
c. To provide access for these ports, holes are cut in the enclosure which match the port locations on the Raspberry Pi.
d. Next I need to find room for the bread board that contains the discrete electronics components to drive the display LEDs. This is the second largest item. There needs to be enough space around it that I can jumper wires to it from the Raspberry Pi and output signals to a header for driving the LEDs. Ideally, if I had more time, I would solder the components and wires directly to the PCB board instead of using a breadboard, but for my purposes its good enough.
e. I plan to have the display driver header next to the breadboard at the edge of the PCB, so that I can keep my wire lengths short, and also so that I can cut a hole in the cover and plug in a cable to the connector.
f. Lastly, I allow room on the PCB for a power block. The system requires 5V for the level shifters and display driver, and 12V for the LEDs. I connect a standard 5V/12V power connector to the power block, then route the power signals from the block to the breadboard and the LED header. I cut a hole in the cover so that I can connect a 12V/5V power cord to the power connector.
g. This is what the final electronics PCB floor plan looks like (with cover off):
Radar speed signspeed signs instantly display a driver's speed, serving as a visual reminder of their current speed compared to the posted limit. This helps drivers become more aware of their actions and encourages them to reduce speed.
e. I plan to have the display driver header next to the breadboard at the edge of the PCB, so that I can keep my wire lengths short, and also so that I can cut a hole in the cover and plug in a cable to the connector.
f. Lastly, I allow room on the PCB for a power block. The system requires 5V for the level shifters and display driver, and 12V for the LEDs. I connect a standard 5V/12V power connector to the power block, then route the power signals from the block to the breadboard and the LED header. I cut a hole in the cover so that I can connect a 12V/5V power cord to the power connector.
g. This is what the final electronics PCB floor plan looks like (with cover off):
Radar speed signs instantly display a driver's speed, serving as a visual reminder of their current speed compared to the posted limit. This helps drivers become more aware of their actions and encourages them to reduce speed.
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