Getting Started
2010 Microchip Technology Inc. DS41401B-page 15
2.6 POWERING WITH THE BLDC EXPANSION HEADER J3
The BLDC Expansion hardware contains a 3.3V linear regulator. This allows the 5-12V
motor power supply to power the PIC16LF1937. J3 pin 6 is the source for the 3.3V
power. To use this power perform the following steps.
1. Make sure a jumper or an ammeter is connected across JP2.
2. Insert the shorting jumper at JP1.
3. Verify that any attached PICkit 3 or PICkit serial is not supplying power.
4. Verify that there is NO power supply or shorting jumper at JP3.
5. Attach the BLDC expansion board.
6. Connect power to the BLDC expansion board.
2.7 DEFAULT FIRMWARE
The default firmware supplied with your F1 Evaluation Board Demo performs the
following functions:
1. Blink LEDs
2. Measure the ambient temperature
3. Run a BLDC motor (or try to if no motor is attached)
4. Display time/temperature/pot position/motor RPM on the LCD
5. User interface with a button and pot
For the latest firmware go to www.microchip.com/F1Eval
2.7.1 Blinking LEDs
The 4 LEDs indicate motor phase operation (D<2:4>) and the performance of the
primary state machine loop (D1).
2.7.2 Measuring the Ambient Temperature
The MCP9800 is polled when in Temperature Measurement mode. The measured
temperature is filtered, scaled to centigrade and displayed on the LCD.
2.7.3 BLDC Motor
One task of the demo code is to drive a BLDC motor attached to the BLDC Expansion
Header. The optional BLDC Controller board (DM164130-2) is required to drive the
motor. The code performs a series of forced commutation steps to attempt a sensorless
motor start. If no back EMF signal is detected, the code repeats the start-up sequence.
The LEDs blink at an increasing rate indicating the motor start attempts. If no motor
drive hardware is attached, this pattern can repeat or it may detect a BEMF signal in
the noise present on the BEMF sense inputs.
