1. MCU Peripherals - Introduction
Parallel Port (GPIO)
Analog-to-Digital converter ADC
Digital-to-Analog converter DAC
Universal Asynchronous Receiver/Transmitter UART (serial port)

2. Pin assignments
LPC213x

3. LPC2131 peripherals

4. General purpose Input Output (GPIO)
CEG2400 Ch8 Peripherals-1 V3b

5. 1) General purpose Input Output (GPIO) http://www. nxp
LPC2131/x has two 32-bit General Purpose I/O ports.
P0[31:0] except P0[31] is output only pin. Pin P0[24]is not available.
P1[31:16] are IOs, P1[1:15] are not available.
Features
Direction control of individual bits
Separate control of output set and clear
All I/O default to inputs after reset
Applications
General purpose I/O
Driving LEDs, or other indicators
Controlling off-chip devices
Sensing digital inputs

6. Exercise 1 What are peripheral modules are available in LPC2131.
Ans: ?__________________
How many parallel input pins and output pins are available in LPC2131?
(i) : Inputs?________________
(ii) : outputs:?__________________
What are the states of the parallel input/output pins after reset: ? ________

7. The experiment hardware
video
switch
Arm board
green led
red led
--We will show how to blink the red-led

8. Our testing board connector p03(pin26) is input, p0. 8(pin33),p0
Our testing board connector p03(pin26) is input, p0.8(pin33),p0.9(pin34) are outputs
CEG2400 Ch8 Peripherals-1 V3b

9. For 3.3V driving LEDs from a 3.3V system

10. Remind you that ARM has Registers (R0-R15) ..etc
32-bit memory addresses total 4-Gbytes
(0x to 0xFFFF FFFF) :
; GPIO Port 0 Register address
IO0DIR EQU 0xE ; IO direction
IO0SET EQU 0xE ; turn on the bits
IO0CLR EQU 0xE002800C;turn off the bits
IO0PIN EQU 0xE ; pin assignment
Registers (R0-R15) ..etc

11. Send data to GPIO registers
; GPIO Port 0 Register address ;
IO0DIR EQU 0xE ; IO direction
IO0SET EQU 0xE ; turn on the bits
IO0CLR EQU 0xE002800C;turn off the bits
IO0PIN EQU 0xE ; pin assignment

12. Explanation2 of GPIO.c (pure polling program) line 1-6
1) #include <lpc21xx.h> //define IO0PIN ,IO0DIR.. etc
2) #define RED_LED 0x //set p0.8 as RED LED
3) #define SW1 0x //set p0.3 as SW1
4) int main(void)
5) { long tmp; // variable for temp storage of port 0 status
//after power up by default all pins are GPIOs, same as PINSEL=0;
6)IO0DIR = RED_LED; // set p0.8 as output
//so IO0DIR=
p0.8=output p0.3=input
// p0.8 is output output, all pins are inputs (include p0.3),
CEG2400 Ch8 Peripherals-1 V3b

13. Explanation3 of GPIO.c (pure polling program) line 7-13
2) #define RED_LED 0x //set p0.8 as RED LED
3) #define SW1 0x //set p0.3 as SW1 :
7) while(1)
8) { tmp =IO0PIN & SW1;//read SW1(p0.3)depressed=0
9) if(tmp==0) ; What happens “if (tmp!=0)” is used?
10) IO0SET = RED_LED; //if SW1 pressed LED is on
11) else IO0CLR = RED_LED; // otherwise off the LED
12) }
13) }
Tmp=0x if SW1 is depressed because p0.3 is 0
Tmp=0x if SW1 is not depressed
P0.3
of LPC213x
CEG2400 Ch8 Peripherals-1 V3b

14. Exercise 2: A simple C program GPIO
Exercise 2: A simple C program GPIO.c When SW1 is depressed, RED-LED is on
1) #include <lpc21xx.h> //define IO0PIN ,IO0DIR.. etc
2) #define RED_LED 0x //set p0.8 as RED LED
3) #define SW1 0x //set p0.3 as SW1
4) int main(void)
5) { long tmp; // variable for temp storage of port 0 status
6) IO0DIR = RED_LED; // set p0.8 as output
7) while(1)
8) { tmp =IO0PIN & SW1;//read SW1(p0.3)depressed=0
9) if(tmp==0) ; What happens “if (tmp!=0)” is used?
10) IO0SET = RED_LED; //if SW1 pressed LED is on
11) else IO0CLR = RED_LED; // otherwise off the LED
12) }
13) }
Question (a): What happens “if (tmp!=0)” is used in line 9?
Ans: ?____________________________________________
Question (b): If the RED-LED is connected to p0.10, how do the program?
Ans: ?______________________________________________
Question (c): If the switch SW1 is connected to p0.4, how do the program?
Ans: ?_______________________________________________________

15. Applications Outputs Inputs Drive LED Drive motor Read on/off switches
Scan keyboard

16. The experiment software in
Assembly or C

17. (i) To drive the GPIO (General Purpose Input Output) using assembly
Step0:
After power, by default, IO pins are set in GPIO mode
Step1:
set GPIO bit direction
Loop Step2:
Read IO pins, check Sw1 status
If sw1 is depressed , goto step4
Step3:
Turn off LED if sw1 is not depressed, goto loop
Step4:
Turn on LED if SW1 is depressed, goto loop

18. A simple assembly program GPIO.s When SW1 is depressed, RED-LED is on
Define registers
Main steps
; GPIO Port 0 Register address ;
IO0DIR EQU 0xE
IO0SET EQU 0xE
IO0CLR EQU 0xE002800C
IO0PIN EQU 0xE
RED_LED EQU 0x ; p0.22=RED LED
SW1 EQU 0x ; p0.20 as SW1 ;
; User Initial Stack & Heap
AREA |.text|, CODE, READONLY
EXPORT __main
__main
1) LDR R1, =RED_LED; p0.22 as output
2) LDR R0, =IO0DIR
3) STR R1,[R0];
4)loop LDR R3, =IO0PIN; read SW1 (p0.22)
5) LDR R3, [R3]
6) TST R3, #SW1;if SW1 depressed R3=0
7) BEQ onled ;if SW1 depressed LEDon
8);
9) LDR R1, =RED_LED;otherwise LEDoff
10) LDR R0, =IO0CLR
11) STR R1,[R0]
12) B loop
13)onled;------ON LED
14) LDR R1, =RED_LED; on the LED
15) LDR R0, =IO0SET
16) STR R1,[R0]
17) B loop
18) END

19. CENG2400 Ch7: driving parallel loads v.3c
Define registers
; GPIO Port 0 Register address
IO0DIR EQU 0xE ; IO direction
IO0SET EQU 0xE ; turn on the bits
IO0CLR EQU 0xE002800C;turn off the bits
IO0PIN EQU 0xE ; address to read pin status ;
;RED_LED EQU 0x ; p0.22=RED LED (out)
; in binary = b, so p..22=out
; by default (reset value) others pins are inputs, so p.20=input
SW1 EQU 0x ; p0.20 as SW1(input) by default reset value
CENG2400 Ch7: driving parallel loads v.3c

20. Main steps 1) LDR R1, RED_LED; p0.22 as output 2) LDR R0, IO0DIR
Step1: set direction of
GPIO pins
p.0.22=output to drive LED
Other pins are inputs
Including
P0.20=input from sw1
1) LDR R1, RED_LED; p0.22 as output
2) LDR R0, IO0DIR
3) STR R1,[R0];
4)Loop LDR R3, IO0PIN; read SW1 (p0.20)
5) LDR R3, [R3]
6) TST R3, #SW1 ;if SW1 depressed (low)
7) BEQ onled ; if SW1 depressed LEDon
8);
9) LDR R1, RED_LED;otherwise LEDoff
10) LDR R0, IO0CLR
11) STR R1,[R0]
12) B loop
13)Onled;
14) LDR R1, RED_LED; on the LED
15) LDR R0, IO0SET
16) STR R1,[R0]
17) B loop
18) END
Step2:
Read IO pins and check
Sw1 status
Parallel port (GPIO) --Driving Parallel Loads
Step3:
Turn off LED if sw1 is not depressed
Step4:
Turn on LED if SW1 is depressed

21. Step1: set GPIO (General Purpose Input Output) bit direction
1) LDR R1, RED_LED; p0.22 as output
2) LDR R0, IO0DIR
3) STR R1,[R0];
Step1: set direction of
GPIO pins
p.0.22=output to drive LED
Other pins are inputs
Including
P0.20=input from sw1
;RED_LED EQU 0x ; p0.22=RED LED (out)
; binary = b, assigns bit 22 as out
; others as inputs
CENG2400 Ch7: driving parallel loads v.3c

22. Step2a: Read IO pins, check Sw1 status
Memory location IOPIN holds the status of Input/output Pins P0.x
I.e.
P0.0 is bit 0 of IOPIN
P0.1 is bit 1 of IOPIN :
P0.20 is bit 20 of IOPIN
Open=1
Closed=0 22

23. Recall: TST and BEQ BEQ TST
Same as AND (logical AND) except result of operation is not stored.
Only the condition code bits (cc) {N,Z,C,V} in CPSR are changed.
updates the N and Z flags according to the result
Does not affect the C or V flags.
BEQ
Branch if result equal to zero (branch if Z=1) 23

24. Step2b: Read IO pins, check Sw1 status
4)Loop LDR R3, =IO0PIN; read SW1(p0.20=bit20 of IOPIN)
5) LDR R3, [R3]
6) TST R3, #SW1 ;if SW1 depressed (IOPIN=0)
;(R3=0) and (#SW1) result is 0, Z flag =1
7) BEQ onled ;if SW1 pressed LEDon,(branch if Z=1)
;If bit 20 of R3 is zero (key depressed) then the zero flag will set by “TST R3,#SW1” and this causes the BEQ to branch to ledon.
See
Read all 32 GPIO p0.0-P0.31 into R3
Since SW1 EQU 0x ; p0.20 (bit20 of IO0PIN)as SW1(input)
Test using TST R3, #SW1 ;meaning“R3 and 0x ”status, check only p0.20
If it is on branch to onled 24
CENG2400 Ch7: driving parallel loads v.3c

25. 12) B loop 9) LDR R1, =RED_LED ; otherwise LEDoff 10) LDR R0, =IO0CLR
Step3:Turn off LED if sw1 is not depressed Defined earlier IO0CLR EQU 0xE002800C RED_LED EQU 0x ; p0.22=RED LED
9) LDR R1, =RED_LED ; otherwise LEDoff
10) LDR R0, =IO0CLR
11) STR R1,[R0]; writes 0x into IO0CLR
; bit 22(p0.22 of IOPIN cleared
12) B loop

26. Step4:Turn on LED if SW1 is depressed Defined earlier IO0SET. EQU
Step4:Turn on LED if SW1 is depressed Defined earlier IO0SET EQU 0xE RED_LED EQU 0x ; p0.22=RED LED
13)Onled;
14) LDR R1,=RED_LED; on the LED
15) LDR R0, =IO0SET
16) STR R1,[R0]; writes 0x into IO0SET
; bit 22(p0.22) of IOPIN set
17) B loop
18) END 26

27. RED_LED EQU 0x00400000; p0.22=RED LED SW1 EQU 0x00100000; p0.20 as SW1
IO0DIR EQU 0xE
IO0SET EQU 0xE
IO0CLR EQU 0xE002800C
IO0PIN EQU 0xE
RED_LED EQU 0x ; p0.22=RED LED
SW1 EQU 0x ; p0.20 as SW1
Exercise 7.3a: Key is not depressed IOPIN=0x Show R0,R1, CPSR( N,Z,V,C ) Current Program Status Register =CPSR, N=negative, Z=zero, V=overflow, C-carry
;_________________________________ R0 , R1 , R3 , NZVC
4)Loop LDR R3, =IO0PIN; read SW1 (p0.3) ; ______________________________
5) LDR R3, [R3] ;______________________________
6) TST R3, #SW1;if SW1 depressed ;______________________________
7) BEQ onled ;if SW1 depressed LEDon ;______________________________
8);
9) LDR R1, =RED_LED;otherwise LEDoff ; ____________________________
10) LDR R0, =IO0CLR ; _____________________________
11) STR R1,[R0] ; _____________________________
12) B loop ; _____________________________
13) onled;------ON LED
14) LDR R1, =RED_LED; on the LED ; _____________________________
15) LDR R0, =IO0SET ; _____________________________
16) STR R1,[R0] ; _____________________________
17) B loop ; _____________________________
18) END

28. RED_LED EQU 0x00400000; p0.22=RED LED SW1 EQU 0x00100000; p0.20 as SW1
IO0DIR EQU 0xE
IO0SET EQU 0xE
IO0CLR EQU 0xE002800C
IO0PIN EQU 0xE
RED_LED EQU 0x ; p0.22=RED LED
SW1 EQU 0x ; p0.20 as SW1
Exercise 7.3b: Key is depressed IOPIN=0x Show R0,R1, CPSR( N,Z,V,C ) Current Program Status Register =CPSR, N=negative, Z=zero, V=overflow, C-carry
;_________________________________ R0 , R1 , R3 , NZVC
4)Loop LDR R3, =IO0PIN; read SW1 (p0.3) ; ______________________________
5) LDR R3, [R3] ;______________________________
6) TST R3, #SW1;if SW1 depressed ;______________________________
7) BEQ onled ;if SW1 depressed LEDon ;______________________________
8);
9) LDR R1, =RED_LED;otherwise LEDoff ; ____________________________
10) LDR R0, =IO0CLR ; _____________________________
11) STR R1,[R0] ; _____________________________
12) B loop ; _____________________________
13) onled;------ON LED
14) LDR R1, =RED_LED; on the LED ; _____________________________
15) LDR R0, =IO0SET ; _____________________________
16) STR R1,[R0] ; _____________________________
17) B loop ; _____________________________
18) END

29. Exercise 7.4 : Modify the previous program to initial the IO pins for the following circuit (Green LED is not used here)
P0.6
P0.5

30. (i) To drive the GPIO (General Purpose Input Output) Using C
A much simpler solution 30

31. A simple C program GPIO.c When SW1 is depressed, RED-LED is on
#include <lpc21xx.h> //define IO0PIN ,IO0DIR.. Etc // see #define RED_LED 0x //set p0.22 as RED LED #define SW1 0x //set p0.20 as SW1 int main(void) { long tmp; // variable for temp storage of port 0 status IO0DIR = RED_LED; // set p0.22 as output while(1) { tmp =IO0PIN & SW1;//read SW1(p0.20)depressed=0 If(tmp==0) ; //What happens “if (tmp!=0)” is used? IO0SET = RED_LED; //if SW1 pressed LED is on else IO0CLR = RED_LED; // otherwise off the LED }

32. Summary
Learned how to interface parallel GPIO (General Purpose Input Output) loads
Learned how to drive LEDs using the ARM MCU

33. 2) Analog-to-Digital converter (ADC)
CEG2400 Ch8 Peripherals-1 V3b

34. 2) Analog-to-Digital converter ADC
Analog voltages
ADC
Light sensor0(IRS0)
Light sensor1(IRS1)
Light sensor2(IRS2)
Light sensor3(IRS3)
Light sensor4(IRS4)
Ad0.0
Ad0.1
Ad0.2
Ad0.3
Ad0.4
Program:
Use
read_sensor (int channel)
To read the data
Applications:
Light sensor (in robot car) ,
temperature sensor,
force sensor.
Video demo:

35. Exercise 3 Code for Analog-to-Digital ADC converter pin assignment for sensor pins
#include <lpc21xx.h>
#define ADCR (*((volatile unsigned long *) 0xE ))
#define ADDR (*((volatile unsigned long *) 0xE ))
int main(void) {
....
//From line 92 of ARMdemo06.c
// We must initialize the IO pin //before using ADC channel
94) PINSEL1 = 0x ; // set p0.27 to ad0.0
95) PINSEL1 |= 0x ; // set p0.28 to ad0.1
96) PINSEL1 |= 0x ; // set p0.29 to ad0.2
97) PINSEL1 |= 0x ; // set p0.30 to ad0.3
98) PINSEL1 |= 0x ; // set p0.25 to ad0.4
Question (a) : Write one instruction to replace of all instructions from line 94 to 98 . Answer: ? ______________________________________________
Question (b) :How to set the system to use ad0.5
Answer:? ________________________________________________

36. PINSEL1 Pin assignment for AD0. 1 94) PINSEL1 = 0x00400000; // set p0
PINSEL1 Pin assignment for AD0.1 94) PINSEL1 = 0x ; // set p0.27 to ad0.0 PINSEL1 = xxxx xxx xxxx xxxx xxxx xxxx bit
Bit23:22
Bit23:22=01
Bit for
ADC
Other bits are
For other
purposes

37. Exercise 4 What is purpose of PINSEL1 register?
ANS: ?____________________________
Where is the location of PINSEL1 register?
What is the pin number of P0.28
How to set P0.28 pin to be the function of ADC0.1?

38. PINSEL1 Pin assignment for AD0.1 94) PINSEL1 |= 0x ; // set p0.28 to ad0.1 PINSEL1 = xxxx xxxx bit
Bit25:24
Bit25:24=01
Ref:
Volume 1: LPC213x User Manual UM10120

39. Exercise 5: Fill in the blanks in the flow diagram of this program Code for Analog-to-Digital ADC converter In C:\Keil\ARM\INC\Philips\lpc21xx.h, ADCR=0xE ADCR=0xE , ADDR=0xE
Conversion not done
From line 71 of ARMdemo06.c
//(1) ADC interface
71) int read_sensor(int channel)
72) {
73) int temp;
74)
75) ADCR=0x1 << ________;//__select channel___
76) ADCR|=_____________; // set up the control bits_
77)
78) while(((temp=ADDR)& ___________)==0); //MSB =1 meaning ADC is done
79) temp>>=6; //?________________________________(bit6->15: 10-bit conversion result)
80) temp&=0x3ff;//TEMP=output IS 0-3V PRESICION IS (10 bits: 2^10=1024 levels)
81)
82) return (temp*33); //?? Why temp*33__________________________
83) }
.....
Loop until
ADC is
done
Explanation ?_______________
Conversion Done
Return temp*scale

40. ADCR -- one (AD0) for lpc2131 line 75) ADCR=0x1<<_______(fill in the blank); line 76) ADCR|=_______(fill in the blank);//operational,start convert ADCR= xxxx xxxx bit
Point to which
channel
Bit 15:8=10b=2
CLKDIV=2+1=3
Freq=13.824MHz/3=4.608MHz
Ref:

41. ADCR -- one (AD0) for lpc2131 line 75) ADCR=0x1<<________(fill in the blank); line 76) ADCR|=_________(fill in the blank);//operational,start convert ADCR= xxxx xxxx bit
Bit21=1 operational
Bit24=1
Ref:

42. Polling for the completion of Analog-to-digital conversion 78) while(((temp=ADDR)&_________(fill in the blank))==0); ADDR= xxxx xxxx xx //MSB =1 meaning ADC is done //if bit 31 of ADDR is 1, it is done //bit 15:6 contain the result
ADC result
CEG2400 Ch8 Peripherals-1 V3b

43. 78)while(((temp=ADDR)&0x80000000)==0);
Find the Analog-to-digital converted result ADC result xx xxxx xxxx ADDR= xxxx xxxx xx
result
78)while(((temp=ADDR)&0x )==0);
79) temp>>=6; temp>>6; = xx xxxx xxxx
80) temp&=0x3ff;//TEMP=output IS 0-3V PRESICION is 1024 (10bit ADC precision)
temp&=0x3ff;= xx xxxx xxxx
82) return (temp*33);// make it a full integer.
polling
result
CEG2400 Ch8 Peripherals-1 V3b

44. 3) Digital-to-Analog converter (DAC)
CEG2400 Ch8 Peripherals-1 V3b

45. 3)Digital-to-Analog converter DAC
Applications
Sound generation, e.g. MP3 player
Motor speed control use analog methods
Usage: Similar to Analog-to-Digital converter ADC
Digital-to-Analog converter DAC --
Convert digital codes into
an analog signal
Analog value

46. DAC reg. 10-bit

47. Universal Asynchronous Receiver / Transmitter UART (serial port)
CEG2400 Ch8 Peripherals-1 V3b

48. 4) Universal Asynchronous Receiver / Transmitter UART (serial port)
//init UART0 setting
......
26) #define NEWLINE sendchar(0x0a); sendchar(0x0d)
33) void Init_Serial_A(void) {
34) U0LCR = 0x83; //8 bit length ,DLAB must be 1 to access
35) U0DLL = 0x0F; //Baud rate setting , part1 36) U0DLM = 0x00; //Baud rate setting , part 2
37) U0LCR = 0x03; //DLAB=0 to complete the setting }
0x0a=New line , 0x0d=carriage return
in ARM06Demo.c, and

49. line34) U0LCR = 0x83; //8 bit length ,DLAB=1 //U0LCR = 1000 0011b
CEG2400 Ch8 Peripherals-1 V3b

50. UART0(baudrate)=PCLK/(16*(16*0+15))
Exercise 6: Baud rate setting 35) U0DLL = 0x0F;//=15 36) U0DLM = 0x00;//=0
Because , PCLK=13.824MHz
UART0(baudrate)=PCLK/(16*(16*0+15))
=13.824MHz/3840=57600 is the baud rate

51. Getchar() in “C” polling method (not interrupt)
40) char getchar(void) {
41) volatile char ch = '0';
42)
43) while ((U0LSR & 0x1)==0)//wait until a byte is received
44) ;
45) ch = U0RBR;// receive character
//(U0RBR - 0xE000 C000,
46)
47) return ch;
48) }
Yes
Is bit1 of U0LSR==0?
(receive buffer empty?)
polling
No,
receive character

52. Sendchar() in “C” polling method (not interrupt)
Is bit6 of U0TH==0?
(Transmitter contains
valid data, previous data
not sent yet?)
Yes
No,
Transmit
Next character
49)////////////////////////////////////////////////////////////
50)void sendchar(char ch) {
51) while( (U0LSR & 0x40)==0 );
52)
53) U0THR = ch;// Transmit next character
54) } // at 0xE000 C000 bit7:0
polling
Bit of U0LSR at 0xE000 C014

53. Print(), Print a string of characters on screen
56) int print(char *p) {
57) while(*p!='\0') { //’\0’ is end of text, = 0x03
58) sendchar(*p++); // if not end of text send characters of the string
59) }
60) return(0);
61)}
......
Example
print(“---Hello world---");NEWLINE;

54. Ascii table from http://enteos2. area. trieste

55. Exercise 7: putint( int count) print an integer on screen
‘0’ is 0x30 (ASCII for number zero)
63) void putint(int count) {
64) sendchar('0' + count/10000);
65) sendchar('0' + (count/1000) % 10); //%=modulus
66) sendchar('0' + (count/100) % 10);
67) sendchar('0' + (count/10) % 10);
68) sendchar('0' + count % 10);
69)}
Question:
If “count” is “2597”, what hex numbers have been sent to the serial port?
Answer: ?_________________________
Print an ASCII character representing that digit at one time,

56. UART main print example
int main(void) {
......
// Initialize IO pin before using TXD0 and RXD0
PINSEL0 = 0x ; // set p0.0 to TXD0, p0.1 to RXD0 and the rest to
GPIO
.....
Init_Serial_A(); // Init COM port
NEWLINE;
print("================================================"); NEWLINE;
print("**"); NEWLINE;
print("* CUHK Computer Science and Engineering Department*"); NEWLINE;
print("* LPC2131 ARM Board (ver1.3) *"); NEWLINE;
print("**"); NEWLINE;
print("* I2C (Master Receiver) Test Program (ver1.3)*"); NEWLINE;

57. 11-Sep-18
Chapter 6 : Serial Interface -- UART (universal asynchronous receiver transmitter ) 57

58. 11-Sep-18
Overview
Introduction to the universal asynchronous receiver transmitter : UART.
UART Hardware Interface
UART Software Interface
Initialize the UART Hardware
Sending data using handshaking 58

59. RS232 standard and application, e.g.
11-Sep-18
1) Introduction: Serial interface (universal asynchronous receiver transmitter : UART)
RS232 standard and application, e.g.
RS232 standard
3 wires
+10 V=‘0’=SPACE
-10V=‘1’=MARK
Pin3
Pin2
pin5
Pin2
Pin3
pin5
RS232 port
(UART)
RS232 port
(UART) 59

60. Serial data transmission means sending data bits one by one.
11-Sep-18
U Universal A Asynchronous R Receiver T Transmitter UART for data communication
Serial data transmission means sending data bits one by one.
Asynchronous transmission means a data (including one start bit , 8-bit data, and stop bits) can be sent at any time. 60

61. Universal asynchronous receiver transmitter : UART
11-Sep-18
Universal asynchronous receiver transmitter : UART
RS232 is a serial communication standard
Since it is asynchronous, no external clock is needed, only 3 wires are required for the simplest RS232 connection (GND, tx, rx)
Bit 0 to 7 (least sig. bit first )
+10V=Logic 0=space
-10V= Logic 1=mark
Start stop
Exercise: Sketch Bit Patterns for character A and B 61

62. ASCII table http://www.cs.utk.edu/~pham/ascii_table.jpg
11-Sep-18
ASCII table 62

63. EXAMPLES Sending ASCII ‘5’=0x35=0011 0101b Oscilloscope Probe
11-Sep-18
EXAMPLES
Sending ASCII
‘5’=0x35= b
Oscilloscope
Probe
The ASCII character has 10 bits
(1 start+8 data + 1 stop bit)
Start bit=0
Stop bit=1
What is this code ?
(stop bit=1)
Least Sign. Bit first
T=bit period
=1/baud rate 63

64. Each bit lasts for (1/Baud rate) seconds
11-Sep-18
If the baud rate is bits per second Define ‘bit period’ :the amount of time to transmit a logic 1 or 0. (bit period= 1/57600 seconds)
Each bit lasts for (1/Baud rate) seconds
bit period =
1/baud rate =(1 / 57600) seconds=17.4 us
Exercise: What is the “bit period” if baud rate is 2400? 64

65. 11-Sep-18
Hello world example
Manual (
Application Note
astartup.s
ahello.s (appendix1)

66. 11-Sep-18
2) UART
Hardware Interface

67. UART Hardware Interface
11-Sep-18
UART Hardware Interface
ARM7 output signals are 0->3.3V.
A MAX232 chip is needed to translate the 0->3.3V levels to the +/-10V RS232 levels (VCC=5V)

68. ARM system support for UART: Memory Map
Ref: page 9 of ARM7-LPC213x-user manual (Hardware Guide, UM10120)
11-Sep-18
ARM system support for UART: Memory Map
Software interface involves appropriately programming registers in the memory map to manipulate the hardware
i.e. from
0xE000 C000 68

69. Like office addresses for mail delivery
11-Sep-18
Like office addresses for mail delivery
UART Office addresses from floor
0xE000 C000 to
0xE000 C030
Memory address space 69

70. Reminded that ARM7 has these registers and memory addresses
11-Sep-18
UART Office
addresses from floor
0xE000 C000 to
0xE000 C030
Reminded that ARM7 has these registers and memory addresses
Registers (R0-R15) ..etc
32-bit memory addresses (0x to 0xFFFF FFFF)

71. Revision
Name the usages of these memory locations in an ARM (LPC21xx) processor
0000 7FFFh ?_______
ROM, code
4000 FFFFh ?_______
RAM, data,Stack
E000 C000 E000 C030 ?_______
(UART)

72. 11-Sep-18
UART Register address map : 0xE000 C000 to 0xE000 C030 U0RBR (read only ) and U0THR (write only) share the same address but have no conflict (because one is for “write” another is for “read”).
Ref: table 96 of ARM7-LPC213x-user manual (Hardware Guide, UM10120)
DLAB=0
DLAB=1 72

73. A general description of the software Interface ahello.s
11-Sep-18
3) UART
A general description of
the software Interface
ahello.s 73
CEG2400 Ch6. Serial Interface -- UART V3a

74. Part3: subroutine to initialize uart0
11-Sep-18
Part3: subroutine to initialize uart0
File name : ahello.s
; UART0 registers
U0RBR EQU 0xE000C000
U0THR EQU 0xE000C000
U0IER EQU 0xE000C004
U0IIR EQU 0xE000C008
U0FCR EQU 0xE000C008
U0LCR EQU 0xE000C00C
U0LSR EQU 0xE000C014
U0SCR EQU 0xE000C01C
U0DLL EQU 0xE000C000
U0DLM EQU 0xE000C004
PINSEL0 EQU 0xE002C000
; User Initial Stack & Heap
AREA |.text|, CODE, READONLY
EXPORT __main
__main BL iuart0
loop MOV R0, #'H'
BL writec
MOV R0, #'e'
MOV R0, #'l'
MOV R0, #'o'
MOV R0, #' '
MOV R0, #'w'
MOV R0, #'r'
MOV R0, #'d'
MOV R0, #'\n'
B loop
iuart0
MOV R1, #0x5 ; PINSEL0 = 0x5
LDR R0, =PINSEL0
STR R1, [R0]
MOV R1, #0x7 ; U0FCR = 0x7
LDR R0, =U0FCR
STRB R1,[R0]
MOV R1, #0x83 ; U0LCR = 0x83
LDR R0, =U0LCR
MOV R1, #0x0f ; U0DLL = 0x0f
LDR R0, =U0DLL
MOV R1, #0x00 ; U0DLM = 0x0
LDR R0, =U0DLM
MOV R1, #0x03 ; U0LCR = 0x03
BX R14 ; return from subroutine
writec LDR R1, =U0LSR
LDRB R1, [R1]
TST R1, #0x40
BEQ writec
LDR R1, =U0THR
STRB R0, [R1]
END
Part1: define registers
Part2: main
program
Part4: subroutine to write data
to serial port 74

75. Part 1 of ahello.s ;send hello to the serial line
11-Sep-18
Part 1 of ahello.s ;send hello to the serial line
Define the address locations of the UART0(Universal asynchronous receiver transmitter) registers ; UART0 registers U0RBR EQU 0xE000C000 U0THR EQU 0xE000C000 U0IER EQU 0xE000C004 U0IIR EQU 0xE000C008 U0FCR EQU 0xE000C008 U0LCR EQU 0xE000C00C U0LSR EQU 0xE000C014 U0SCR EQU 0xE000C01C U0DLL EQU 0xE000C000 U0DLM EQU 0xE000C004 PINSEL0 EQU 0xE002C000
RS232 standard
3 wires
+10 V=‘0’=SPACE
-10V=‘1’=MARK
Pin3
Pin2
pin5
Pin2
Pin3
pin5
RS232 port
(UART)
RS232 port
(UART) 75

76. 11-Sep-18
Define Uart Registers in assembly (in lpc21xx.h (ARM7) generated by uvision3 of the Keil assembler tool)
; UART0 registers U0RBR EQU 0xE000C000 U0THR EQU 0xE000C000 U0IER EQU 0xE000C004 U0IIR EQU 0xE000C008 U0FCR EQU 0xE000C008 U0LCR EQU 0xE000C00C U0LSR EQU 0xE000C014 U0SCR EQU 0xE000C01C U0DLL EQU 0xE000C000 U0DLM EQU 0xE000C004 PINSEL0 EQU 0xE002C000
EQU Pseudo instruction
Define a constant
X EQU 2
This is an assembler directive that is used to give a value to a label name. In this example it assigns X the value 2. Thus when X is used elsewhere in the code, the value 2 will be substituted (similar to using a #define to set up a constant in the C language). 76

77. Part 2 of ahello.s ;send hello to the serial line
11-Sep-18
; User Initial Stack & Heap
AREA |.text|, CODE, READONLY
EXPORT __main
__main BL iuart0
loop MOV R0, #'H'
BL writec
MOV R0, #'e'
MOV R0, #'l'
MOV R0, #'o'
MOV R0, #' '
MOV R0, #'w'
MOV R0, #'r'
MOV R0, #'d'
MOV R0, #'\n'
B loop
Part 2 of ahello.s ;send hello to the serial line
In this program, it writes “hello world” to the serial line.
Print
hello
world

78. Part 3 of ahello.s, (subroutine iuart0: initialize uart0 registers)
11-Sep-18
Part 3 of ahello.s, (subroutine iuart0: initialize uart0 registers)
iuart0
MOV R1, #0x5 ; PINSEL0 = 0x5
LDR R0, =PINSEL0
STR R1, [R0]
MOV R1, #0x7 ; U0FCR = 0x7
LDR R0, =U0FCR
STRB R1,[R0]
MOV R1, #0x83 ; U0LCR = 0x83
LDR R0, =U0LCR
MOV R1, #0x0f ; U0DLL = 0x0f
LDR R0, =U0DLL
MOV R1, #0x00 ; U0DLM = 0x0
LDR R0, =U0DLM
MOV R1, #0x03 ; U0LCR = 0x03
BX R14
; return from subroutine 78

79. 11-Sep-18
Part 4 of ahello.s (subroutine writec: write one character to the serial line)
writec LDR R1, =U0LSR LDRB R1, [R1] TST R1, #0x40 BEQ writec LDR R1, =U0THR STRB R0, [R1] BX R14 ; return from ;subroutine END 79

80. 4) Detailed description of subroutines “iuart0” in ahello.s
11-Sep-18
4) Detailed description of subroutines “iuart0” in ahello.s
Initialize the UART Hardware
Setup data into UART registers
UART registers
0xE000 C000 to
0xE000 C030 80
CEG2400 Ch6. Serial Interface -- UART V3a

81. 11-Sep-18
Subroutine iuart0: Software to initialize the UART in the LPC21xx (ARM7) chipset
inside iuart0
Step 1: setup pins
configure pin function select reg. i.e. pin 19=TXD
Step 2
configure FIFO control reg.
Step 3
configure line control reg. (start, stop bits)
Step 4
Configure baud rate 81

82. Part 3 of ahello.s Initialize uart0 (iuart0) in ahello.s (Appendix1)
11-Sep-18
Part 3 of ahello.s Initialize uart0 (iuart0) in ahello.s (Appendix1)
step4
Step1:
setup pins
MOV R1, #0x0f
LDR R0, =U0DLL
STRB R1,[R0]
MOV R1, #0x00;
U0DLM = 0x0
LDR R0, =U0DLM
STRB R1,[R0]
iuart0 MOV R1, #0x5 LDR R0, =PINSEL0 STR R1, [R0] MOV R1, #0x7 LDR R0, =U0FCR STRB R1,[R0] MOV R1, #0x83 LDR R0, =U0LCR
step2
step3 82

83. Step1 of iuart0: pin configuration=0x05
11-Sep-18
Step1 of iuart0: pin configuration=0x05
Configure the pin for serial interfaces
Arm7 pins are multi functions, depending on initialization.
E.g. configure pin-symbol “p0.0” (pin19 or p0.0) to be the serial transmission pin “TXD”
You must set Bit 1:0 of address 0xE002 C000=“01”. 83

84. 11-Sep-18
Exercise 6.1 : which pin (what Px,y) is RXD? PINSEL0--pin function select reg. [0XE002 C000]=0x05 bit0, bit 2are 1
Somewhere inside there
Setup
Pin19 or
P0.0 to have
the function
of TXD 84

85. 11-Sep-18
Exercise 6.1 : which pin (what Px,y) is RXD? Answer: P0.1or pin21 PINSEL0--pin function select reg. [0XE002 C000]=0x05 bit0, bit 2are 1
Setup
Pin19 or
P0.0 to have
the function
of TXD
Answer: Setup
Pin21 or
P0.1 to have
the function
of RXD 85

86. Step2 of iuart0:—setup FIFO control
11-Sep-18
Step2 of iuart0:—setup FIFO control
Step4
Set
Baud=
57600
Step1:
setup pins
iuart0 MOV R1, #0x5 LDR R0, =PINSEL0 STR R1, [R0] MOV R1, #0x7 LDR R0, =U0FCR STRB R1,[R0] MOV R1, #0x83 LDR R0, =U0LCR
MOV R1, #0x0f
LDR R0, =U0DLL
STRB R1,[R0]
MOV R1, #0x00;
U0DLM = 0x0
LDR R0, =U0DLM
STRB R1,[R0]
Step2:
setup First IN
First Out
( FIFO) control
step3
What do all of these values do? 86

87. Step2:U0FCR--FIFO control set reg=0x07 [U0FCR]=0x07
11-Sep-18
Step2:U0FCR--FIFO control set reg=0x07 [U0FCR]=0x07
Set all
bit0,1,2=“111”
for FIFO control 87

88. 11-Sep-18
Step3 of iuart0: Exercise 6.2, Circle which bits are set,discuss their functions. U0LCR—line control set reg=0x83 [U0LCR]=0x83 88

89. 11-Sep-18
Exercise 6.2a, which bits are set, and their functions. Answer:8-bit character length, 1 stop bit, no parity, enable division latch Step3:U0LCR—line control set reg=0x83, set reg [U0LCR]= =0x83= B
[U0LCR]=
0x83= B
Exercise2b: Repeat exercise2a but 7bit data, 1 stop bit , no parity Answer: U0LCR= b=0x82 89

90. 11-Sep-18
Step2 of iuart0:U0DLL—set baud rate=0x0F [U0DLL]=0x0F, set Baudrate=576000
U0DLL = Fpclk / (16 * Baudrate)
If we want baud (Fpclk=13.824MHz) then U0DLL=15=0x0f (U0DLM(for msc)=00;U0DLL(for lsb)=15)
Check datasheet of how it should be set.
Exercise4a: How to set the baud rate to be 9600?
Answer4: U0DLL9600 = Fpclk / (16 * Baudrate)
=13.824MHz / (16 * 9600)=90
Also U0DLM9600 =00
Exercise4b: How to set Baud rate = 2400?
Useful tool:
/(16(16M+L))=2400
/(16*2400)=360=16M+L
M=?_____, L=?_____ 90

91. 11-Sep-18
5) Detailed description of subroutines “writec” : Sending data using handshaking 91

92. 11-Sep-18
Subroutine Writec: Basic concept of sending a character using the serial port
The sending procedure is slower (e.g. only bits per second) than your program, so it needs to ask permission to send
Writec()
Sending rate (Baud rate)
is slower than your program can gen. data
True even for usb2
receiver
Send-buffer
Is transmitter
Buffer empty ? no
yes
Send data

93. Read buffer status U0LSR(0xE000 C014)
11-Sep-18
Read buffer status U0LSR(0xE000 C014)

94. 11-Sep-18
U0LSR—line status at U0LSR(0xE000 C014) (if bit6=TEMT (transmitter empty)=1 you can send next data
Bit Bit0

95. Recall: TST and BEQ BEQ TST
11-Sep-18
Recall: TST and BEQ
TST
Same as AND (logical AND) except result of operation is not stored.
Only the condition code bits (cc) {N,Z,C,V} in CPSR are changed.
updates the N and Z flags according to the result
Does not affect the C or V flags.
BEQ
Branch if result equal to zero (branch if Z=1) 95

96. 1)Writec ; subroutine to send data in R0 to serial out
11-Sep-18
Write character in R0 subroutine when TEMT=1 TEMT=0 meaning transmitter is not empty, not ready to send TEMT=1 meaning transmitter is empty, ready to send
1)Writec ; subroutine to send data in R0 to serial out
2) LDR R1, =U0LSR; (line status reg)
3) LDRB R1, [R1]; get line status
TST R1, #0x40 ;TEMT(bit 6 of ;U0LSR=1=buffer_empty)=0Z=1
5) BEQ writec ;if Z=1(buffer_not_empty),
;loop back writec to wait
6) LDR R1, =U0THR;U0THR=transmit reg
7) STRB R0, [R1]; send data out
8) BX R14 ; return from subroutine
TST : same as “AND”, but result is not saved , affect Z bit in cpsr

97. 11-Sep-18
Flow diagram of Writec of ahello.s TEMT=0 meaning transmitter is not empty, not ready to send TEMT=1 meaning transmitter is empty, ready to send
Reason: The sending speed (Bit per second) is slower than your program, need to ask permission to send
Writec( ); write data in R0
4)TST R1, #0x40 ;TEMT=0 (buffer_not _empty: transmitter not ready) Z=1
;TEMT=1 (buffer_empty: transmitter is ready) Z=0
Brach if Z=1
5) BEQ writec
If Z=1
Is the transmitter buffer is not empty, loop back.
Because TEMT=0 Z=1,
BEQ writec ;if Z=1,loop back to wait
Otherwise send data
If Z=0
6) LDR R1, =U0THR
7) STRB R0, [R1]; send data out

98. Summary Studied serial interface in ARM
11-Sep-18
Summary
Studied serial interface in ARM
Studied handshaking in interfacing

99. 11-Sep-18
End 99

100. Summary
Studied peripherals of the LPC213x ARM processor.

101. Appendix

102. Appendix (1) Watchdog timer register setting
If the system doesn’t give
me any signals for a period
of time (say 2 seconds), that
means it hangs, so I will
Press the reset bottom