MicRoCon – Micro Robotics Controller for Raspberry Pi
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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