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Getting to Know Your MicRoCon

MicRoCon – Micro Robotics Controller for Raspberry Pi

Microcon3_01a

This is the baby sister to our full-featured PiRoCon controller board. It still features two bi-directional motor controllers, a 5V regulator for the Raspberry Pi as well as general purpose IO connectors, 5V servo outputs and a 4-pin Ultrasonic input.

Motors A & B

  • Motor A: Pins 24, 26 (GPIO: CE0 and CE1)
  • Motor B: Pins 19, 21 (GPIO: MOSI, MISO)
  • Permanently enabled
  • Use either pin for each motor with PWM
  • Remember to invert the PWM duty cycle when reversing
  • Motors are driven via an L293D H-Bridge chip from the input voltage at the 2-pin terminal (not from the regulated 5V supply)

 

 GPIO Connections

  • These are NOT level-shifted and only work with 3.3V devices. Do not connect a 5V input
  • Each GPIO pin has an asdsociated Ground and 3.3V pin so can connect 3-pin sensors directly
  • Pin 7 (GPIO: 04)
  • Pin 11 (GPIO: 17)
  • Pin 12 (GPIO: 18)
  • Pin 13 (GPIO: 27)

 

Servos

  • These 2 sets of 3 pins provide outputs to drive 5V servos
  • The signals are not level-shifted but all servos I have tried work happily with a 3.3V input signal
  • Servo 1: Pin 18 (GPIO 22)
  • Servo 2: Pin 22 (GPIO 25)

 

Ultrasonic Input

  • These four pins allow an HC-SR04 4-pin ultrasonic sensor to be connected directly
  • This uses a resistor network to allow the sensor to use only a single GPIO pin, which is shared between Ping/Trig and Echo
  • Output a pulse using the pin in output mode
  • Then switch to input mode to await the response
  • This is connected to Pin 8 (GPIO: Txd)

 

Regulator

  • This uses an L4040V5 linear low dropout regulator
  • The input voltage can go as low as 6V and the output will remain at 5V
  • The higher the input voltage, the hotter the regulator will get in use
  • The motors do not use the regulated voltage so will have no effect on the temperature of the regulator

 

I2C Female Header

  • Allows easy access to the I2C signals SCL and SDA
  • Also provides 0V, 3.3V and 5V connections
  • Same pinout as used on the PiRoCon expansion header so all expansion boards for the PiRoCon can also be fitted to the MicRoCon – ADC, 16-channel PWM available right now.
  • You can use the 4tronix IP Display dongle directly into this header.

 

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