Sensors, Shields, and Wifi

[project_science]

Hi,

I’m designing an indoor project where a wooden beam will be hung horizontally on a wall, about 20 feet in length. There will be 5 sensors on the beam, each spaced 4 feet apart. They will be facing toward the room, and sensing people as they walk by. I’m assuming the beam will be 4-5 feet off the ground.

Questions:

1. Sensors - Which type of sensor should I use which will accomplish the following:
- Minimize crosstalk / false echos between the beams (narrow beam width?)
- Be able to detect a person walking by it, about 2-4 feet (3 feet is ideal)

Note: I have already tried the HC-SR04 sensor, and the ranges,during my testing were inconsistent, and could barely get up to 170cm, and some didn’t go over 70cm. The product is quoted at about 400cm range.

2. Pin Issues - This project will (probably) be run off of an UNO. When a sensor is tripped, it should make several motors spin. I’m thinking about using: https://www.adafruit.com/products/154

These will probably be run off of a servo shield: https://www.adafruit.com/products/1411

So here’s the question: If I use these components:

- UNO
- Servo Shield
- 5 sensors (e.g. sonar, or whatever you recommend)

a) Will there be any pin issues?
b) Will 4 continuous rotation servos be able to rotate at the same time, if driven off the servo shield?

3. Data Logging. If I throw this shield into the stack: https://www.adafruit.com/products/1141

Will there be any pin issues overlapping as I save to the SD card?


4. Wifi - I was initially thinking about using this board to send data over wifi: https://www.adafruit.com/products/2891, however, it is out of stock (and has been for a while.) However, I found this new one, which seems just like my UNO, except has Wifi capabilities built in:

http://world.arduino.org/en/arduino-uno-pro.html

Would this work OK instead of the basic UNO (without pin issues?)

If not, unless you have a better method for getting this project to send over wifi, I suppose I can use a digital pin output from the UNO to a different board, e.g. a Feather board with Wifi, such as: https://www.adafruit.com/products/3061

What do you think of these suggestions?

[adafruit_support_bill]

1 - For sensors, I would recommend the Maxbotix ultrasonic sensors. They have well defined beam patterns, work well at that range and can be synchronized to avoid crosstalk between sensors.

2a - 5 ultrasonic sensors will need 5 analog pins. Since the UNO shares 2 analog pins with the i2c bus (needed for the servo shield), you will only have 4 to work with. The Leonardo was discontinued, but the Seeduino Lite is a suitable replacement. It allows you to use all 6 analog pins and the i2c at the same time:
https://www.adafruit.com/products/3228l

2b - no problem

3 - That should work fine. The RTC can share the i2c bus with the servo shield.

4 - The Arduino WiFi has the same pin issues as the UNO. We do have the Seeed Studio WiFi shields: https://www.adafruit.com/products/2971

You could also go with one of the Feathers - like the 32U4 AdaLogger, then stack a WiFi Wing and a Servo Wing:
https://www.adafruit.com/products/2795
https://www.adafruit.com/products/2928
https://www.adafruit.com/products/3056