1. Microcontrollers BME 201

2. Overview Microcontrollers Notation Registers Timer Concepts Equations

3. Microcontrollers Made of millions of electrical components A little computer http://upload.wikimedia.org/wikipedia/commons/4/4c/PIC_microcontrollers.jpg

4. Programming High-Level Language Assembly Language Machine Language Easy-to-understand abstract language 0 s or 1 s Hard to understand Defined by manufacturer a = b + cAdd a, b, c0110110110110111

5. Instruction Fetch and Execute 1.Fetch the instruction 2.Figure out what it is 3.Load the operands 4.Do the operation 5.Store the results (if necessary)

6. Notation Decimal (base 10): 0 – 9 1234 = (1x10 3 )+(2x10 2 )+(3x10 1 )+(4x10 0 )

7. Notation Binary (base 2): 0 or 1 0b0110 = (0x2 3 )+(1x2 2 )+(1x2 1 )+(0x2 0 ) = 0 + 4 + 2 + 0 = 6 k

8. Notation Hexadecimal (base 16): 0 – 9, A – F A = 10 B = 11 … 0x5A0F = (5x16 3 )+(10x16 2 )+(0x16 1 )+(15x16 2 ) = 23055 a

9. Notation Page 49 of Handbook 0b00101011 0x2 B BinaryHex 00000 00011 00102 00113 01004 01015 01106 01117 BinaryHex 10008 10019 1010A 1011B 1100C 1101D 1110E 1111F

10. Data Types Char – Single character: ‘a’, ‘f’, ‘\n’ Int – Whole number: 8, 124, -873 Double/Float – Decimal Number: 4.6, -2.7 Array – Collection of similar data: [1, -4, 3] String – ‘String’ of characters: “Hello World!”

11. Registers

12. Timer

13. Bit-Size 8-bit Counts 0 to (2 8 – 1) 0x00, 0x01, 0x02, … 0xFD, 0xFE, 0xFF 16-bit Counts 0 to (2 16 – 1) 0x0000, 0x0001, 0x0002, … 0xFFFD, 0xFFFE, 0xFFFF

14. Overflow 0x00 + 1 = 0x01 0x01 + 1 = 0x02 … 0x0F + 1 = 0x10 0x10 + 1 = 0x11 … 0xFE + 1 = 0xFF 0xFF + 1 = ?

15. Incrementing Counter Counter increments every instruction executed Each instruction executes in 4 clock cycle

16. Prescale Scales the increment rate 1:2, 1:4, 1:8, 1:32, 1:64, 1:128, 1:256

17. Start Bytes Start at a specific value 8-bit 0x00 TMR0L 16-bit 0x0000 TMR0H|TMR0 L

18. Timer Equation 1.Calculate timer increment 1.Determine bit-size 2.Calculate prescale 3.Calculate X (start bytes)

19. Registers T0CON TMR0H TMR0L Overflow: TMR0IF