1 / 18

PIC interfacing workshop 2

PIC interfacing workshop 2. Note consultation hours – Prof. Michael Peshkin, B227 Tech.  Monday 9-10 & 4-6.   Wednesday 9-10 & 4-6.    Friday 9-10.   Prof. Kevin Lynch, B221 Tech.  Tuesday 2-5.   Thursday 2-3. http://hades.mech.northwestern.edu/wiki. PIC 18F4520 – what can it do?.

deborah-prince
Download Presentation

PIC interfacing workshop 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. PIC interfacing workshop 2 • Note consultation hours – • Prof. Michael Peshkin, B227 Tech.  • Monday 9-10 & 4-6.   • Wednesday 9-10 & 4-6.    • Friday 9-10.   • Prof. Kevin Lynch, B221 Tech.  • Tuesday 2-5.   • Thursday 2-3. http://hades.mech.northwestern.edu/wiki

  2. PIC 18F4520 – what can it do? ~35 digital input lines (sensors) ~35 digital output lines (on/off) 8 analog inputs (ADC), 10-bit resolution 0 analog outputs! 2 PWM outputs (pulse width modulation, often for running motors) RS-232 serial communication I2C serial communication Interrupts 4 timers & counters

  3. #include <18f4520.h> #DEVICE ADC=10 // set ADC to 10 bit accuracy #fuses HS,NOLVP,NOWDT,NOPROTECT #use delay(clock=20000000) int16 value; //f ro 10-bit res void main() { setup_adc_ports(AN0_TO_AN3); setup_adc(ADC_CLOCK_INTERNAL); while (TRUE) { set_adc_channel(0); delay_us(10); value = read_adc(); output_d(value>>2); if (value > 320) output_high(PIN_C0); else output_low(PIN_C0); delay_ms(10); } } Analog inputs; light measurements

  4. Adjusting a variable value easily with a potentiometer set_adc_channel(0); delay_us(10); value = read_adc();

  5. Digital inputs and outputs; magnetic sensing int onebyte, onebit; ... onebyte = input_c(); output_d(onebyte); onebit = input(PIN_C1);

  6. Driving high current devices from a digital output Possible high-current device: a solenoid

  7. Strobed light: more sensitivity less background light dependence set_adc_channel(0); delay_us(10); originalvalue = read_adc(); output_high(PIN_C0); // turn LED on delay_us(70); newvalue = read_ADC(); extralight = newvalue – oldvalue; Amplified phototransistor for strobed light

  8. PWM for bidirectional variable speed control of a motor

  9. 1. Motor + 2. +5V (or similar) to power the encoder3. Encoder channel A4. Encoder channel B5. GND for the encoder6. Motor -

  10. Controlling RC servos 0.3mS < t < 2.5mS T ~ 20mS Servo’s rotor position depends on t Waveform can be generated by PIC software; see RCservoSoft.c

  11. Serial output (“printf”) 2 line LCD uses RS232 code with a 0V/5V convention PC’s “comm port” uses RS232 code with a -7/+12V convention

  12. #include <18f4520.h> #fuses HS,NOLVP,NOWDT,NOPROTECT #use delay(clock=20000000) // 20 MHz crystal on PCB #use rs232(baud=19200, UART1) // hardware UART; //uses RC6/TX and RC7/RX int16 i; int j; void main() { while (TRUE) { for (i=1; i<10000; i++) { printf("Hello world. %Lu %u\r\n", i, j); delay_ms(100); if (kbhit()) j = getc(); } } }

  13. Keeping it neat....

  14. Bend sensor or “whisker”

  15. Analog Hall sensor (as opposed to digital Hall switch) 0-5V output depending on field (-1000 to +1000 gauss)

  16. Contact: limit switches

  17. Detecting a nearly ferrous but not magnetized object

More Related