Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] Department of EIE / PEC UART in LPC2148 Dr.R.Sundaramurthy Department of EIE Pondicherry Engineering College [email protected]
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Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
UART in LPC2148
Dr.R.SundaramurthyDepartment of EIE
Pondicherry Engineering College
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
UART
• Two Identical UARTs UART0 & UART1
• We are using UART0 for our example.
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Pins Involved
P0.0 [Pin 19] TXD0
P0.1 [Pin 21] RXD0
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
SFRs Involved
• P0 Pin Select Register - PINSEL0
• UART0 Line Control Register - U0LCR
• UART0 Line Status Register - U0LSR
• UART0 Divisor Latch MSB - U0DLM
• UART0 Divisor Latch LSB - U0DLL
• UART0 Transmit Holding Register - U0THR
• UART0 Receive Buffer Register - U0RBR
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Pin Select SFRs
• PINSEL0 for GPIO pins 0.0 to 0.15
• PINSEL1 for GPIO pins 0.16 to 0.31
• PINSEL2 for GPIO pins 1.16 to 1.31
Each Pin is Associated with multiple functions
Pin Select enable you to select which pin
functions you would like to use
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
How to Use PINSEL
• Each associated 'pin' in PINSEL0 and PINSEL1 is assigned a 2-bit address.
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Function Selection Bits
Example for P0.0 & P0.1 as TxD & RxD
PINSEL0 = 0x00000005
0 1 0 1
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
UART0 Line Control Register - U0LCR
U0LCR = 0x00000083;
1 1 1
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
UART0 Line Status Register - U0LSR
Bit – 0 : Receive Data Ready (RDR)
Bit – 5 : Transmit Holding Register Empty (THRE)
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Baud Rate Clock
U0DLM U0DLL
195 (Or) 0xC3
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Baud Rate Calculations
Divisor = Pclk / (Baud x 16)
= 60 x 10^6 / (9600 x 16)
= 391
= 0x01 87
U0DLM = 0x01
U0DLL = 0x87
Divisor = Pclk / (Baud x 16)
= 30 x 10^6 / (9600 x 16)
= 195
= 0x00 C3
U0DLM = 0x00
U0DLL = 0xC3
For Pclk = 60MHzFor Pclk = 30MHz
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Divisor Latch
• UART0 Divisor Latch MSB - U0DLM
• UART0 Divisor Latch LSB - U0DLL
• Holds the value used to divide the clock supplied by the prescaler in order to produce the baud rate clock.
• The Divisor Latch Access Bit (DLAB) in U0LCR must be one in order to access the UART0 Divisor Latches
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
UART0 Receive Buffer - U0RBR
• The U0RBR is the top byte of the UART0 Rx FIFO
• The Divisor Latch Access Bit (DLAB) in U0LCR must be zero in order to access the U0RBR
• The U0RBR is always Read Only
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
UART0 Transmit Holding Register - U0THR
• The U0THR is the top byte of the UART0 TX FIFO.
• The Divisor Latch Access Bit (DLAB) in U0LCR must be zero in order to access theU0THR.
• The U0THR is always Write Only
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Algorithm for Initializing UART0
1. Generate Pclk for 30MHz VPBDIV = 0X00000002;
2. Select UART Function for the PinsPINSEL0 = 0X00000005;
3. Set UART0 Line Control Register for 8 Bit UART, No Parity ,1 Stop Bit with Divisor Latch Access Bit (DLAB) Enabed.
U0LCR = 0X00000083;4. Set U0DLL & U0DLM for 9600 Baud.
U0DLL = 0XC3;U0DLM = 0X00;
5.Clear Divisor Latch Access Bit (DLAB)U0LCR = 0X00000003;
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Initialization Routine
void initserial(void){VPBDIV = 0X02;PINSEL0 =0X00000005; U0LCR = 0X00000083;U0DLL = 0XC3;U0DLM = 0X00;U0LCR = 0X00000003;}
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
• Move the data to be transmitted to UART0 Transmit Holding Register.
U0THR = mydata;
Wait until Transmit Holding Register Empty is set.
while((U0LSR & 0x20)==0);
Algorithm for Transmitting Data using UART0
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Send Serial Routine
void sendserial(unsigned char serdata)
{
U0THR = serdata;
while((U0LSR & 0x20)==0);
}
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Wait until Receive data Ready Flag is set.
while((U0LSR & 0x01)==0);
• Move the received data from UART0 Receive Buffer Register .
temp = U0RBR ;
Algorithm for Receiving Data using UART0
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Receive Serial Routine
unsigned char ReceiveSerial(void)
{
unsigned char mydata ;
while((U0LSR & 0x01)==0);
mydata = U0RBR ;
return mydata;
}
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
UART.h
• void initserial(void);
• void sendserial(unsigned char serdata);
• unsigned char receiveserial(void);
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
initserial
void initserial(void)
{
PINSEL0 =0X05;
// P0.0 = TxD , P0.1 = RxD
U0LCR = 0X83;
// DLAB(7) = 1 , 8 Bit UART (1,0) = 1,
U0DLL = 0X87;
// = 60 x 10^6 / (9600 x 16) = 391 = 0x0187
U0DLM = 0X01; // 9600 Baud
U0LCR = 0X03; // DLAB(7) = 0,8 Bit UART (1,0) = 1,
}
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
sendserial
void sendserial(unsigned char serdata)
{
U0THR = serdata;
// Move data to be transmitted to U0THR
while((U0LSR & 0x20)==0);
// wait until THR Empty Flag is set.
}
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
receiveserial
unsigned char receiveserial(void)
{
unsigned char mydata ;
while((U0LSR & 0x01)==0);
// wait until RBR Full Flag is set.
mydata = U0RBR ;
// Move data Received to U0THR
return mydata;
}
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Question
1. Transmit a constant string of “WELCOME TO EIE” at a rate of 9600 Baud to PC with a time delay.
2. Design a PC based control system to receive data from PC and to perform the following operations.
A P1.25 – ON
B P1.25 – OFF
C P1.26 – ON
D P1.26 – OFF
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Problem-1 (Transmit Serial) #include<lpc214x.h>
#include "GPIO.h"
#include "timer.h"
#include "UART.h"
// UART Transmit
unsigned char UARTdata[14]
= "Welcome to EIE" ;
int i;
int main(void)
{
initPLL(); // 60 MHz Pclk
initserial();
while(1)
{
for(i=0;i<14;i++)
sendserial(UARTdata[i]);
sendserial(13); // carriage return
sendserial(10); // Line feed
delayms(1000);
}
}
XTAL162
XTAL261
P0.0/TxD0/PWM119
P0.1/RxD0/PWM3/EINT021
P0.2/SCL0/CAP0.022
P0.3/SDA0/MAT0..0/EINT126
P0.4/SCK0/CAP0.1/AD0.627
P0.5/MISO0/MAT0.1/AD0.729
P0.6/MOSI0/CAP0.2/AD1.030
P0.7/SSEL0/PWM2/EINT231
P0.8/TxD1/PWM4/AD1.133
P0.9/RxD1/PWM6/EINT334
P0.10/RTS1/CAP1.0/AD1.235
P0.11/CTS1/CAP1.1/SCL137
P0.12/DSR1/MAT1.0/AD1.338
P0.13/DTR1/MAT1.1/AD1.439
P0.14/DCD1/EINT1/SDA141
P0.15/RI1/EINT2/AD1.545
P0.16/EINT0/MAT0.2/CAP0.246
P0.17/CAP1.2/SCK1/MAT1.247
P0.18/CAP1.3/MISO1/MAT1.353
P0.19/MAT1.2/MOSI1/CAP1.254
P0.20/MAT1.3/SSEL1/EINT355
P0.21/PWM5/AD1.6/CAP1.31
P0.22/AD1.7/CAP0.0/MAT0.02
P0.2358
P0.25/AD0.4/AOUT9
P0.27/AD0.0/CAP0.1/MAT0.111
P0.28/AD0.1/CAP0.2/MAT0.213
P0.29/AD0.2/CAP0.3/MAT0.314
P0.30/AD0.3/EINT3/CAP0.015
V323
RST57
VREF63
VSS6
VSSA59
P1.16/TRACEPKT016
P1.17/TRACEPKT112
P1.18/TRACEPKT28
P1.19/TRACEPKT34
P1.20/TRACESYNC48
P1.21/PIPESTAT044
P1.22/PIPESTAT140
P1.23/PIPESTAT236
P1.24/TRACECLK32
P1.25/EXTIN028
P1.26/RTCK24
P1.27/TDO64
P1.28/TDI60
P1.29/TCK56
P1.30/TMS52
P1.31/TRST20
V343
V351
VSS18
VSS25
VSS42
VSS50
RTXC13
RTXC25
V3A7
VBAT49
P0.3117
P0.26/AD0.510
U1
LPC2138
+3.3V
12
X1
C1
33pF
C2
33pF
12
X2
C3
22pF
C4
22pF
R11K
C5100pF
+3.3V
Xmodem, Ymodem, Zmodem
VT52, VT100, ANSIRXD
RTS
TXD
CTS
T1IN11
R1OUT12
T2IN10
R2OUT9
T1OUT14
R1IN13
T2OUT7
R2IN8
C2+
4
C2-
5
C1+
1
C1-
3
VS+2
VS-6
U2
MAX232
C6
1uF
C7
1uF
C81uF
C91uF
LOAD-1
LED-YELLOW
LOAD-2
LED-YELLOW
Dr.R.Sundaramurthy.,M.E.,Ph.D., [email protected] of EIE / PEC
Problem-2 (Receive Serial) #include<lpc214x.h>
#include "GPIO.h"
#include "timer.h"
#include "UART.h"
// PC based Home Automation
int ON = 0;
int OFF = 1 ;
int Load1 = 25;
int Load2 = 26;
unsigned char UARTdata;
int main(void)
{
initPLL(); // 60 MHz Pclk
initserial();
while(1)
{
UARTdata = receiveserial();
if (UARTdata == 'A')
writepin(Load1,ON);
else if (UARTdata == 'B')
writepin(Load1,OFF);
else if (UARTdata == 'C')
writepin(Load2,ON);
else if (UARTdata == 'D')
writepin(Load2,OFF);
else
{
writepin(Load1,OFF);
writepin(Load2,OFF);
}
}
}
XTAL162
XTAL261
P0.0/TxD0/PWM119
P0.1/RxD0/PWM3/EINT021
P0.2/SCL0/CAP0.022
P0.3/SDA0/MAT0..0/EINT126
P0.4/SCK0/CAP0.1/AD0.627
P0.5/MISO0/MAT0.1/AD0.729
P0.6/MOSI0/CAP0.2/AD1.030
P0.7/SSEL0/PWM2/EINT231
P0.8/TxD1/PWM4/AD1.133
P0.9/RxD1/PWM6/EINT334
P0.10/RTS1/CAP1.0/AD1.235
P0.11/CTS1/CAP1.1/SCL137
P0.12/DSR1/MAT1.0/AD1.338
P0.13/DTR1/MAT1.1/AD1.439
P0.14/DCD1/EINT1/SDA141
P0.15/RI1/EINT2/AD1.545
P0.16/EINT0/MAT0.2/CAP0.246
P0.17/CAP1.2/SCK1/MAT1.247
P0.18/CAP1.3/MISO1/MAT1.353
P0.19/MAT1.2/MOSI1/CAP1.254
P0.20/MAT1.3/SSEL1/EINT355
P0.21/PWM5/AD1.6/CAP1.31
P0.22/AD1.7/CAP0.0/MAT0.02
P0.2358
P0.25/AD0.4/AOUT9
P0.27/AD0.0/CAP0.1/MAT0.111
P0.28/AD0.1/CAP0.2/MAT0.213
P0.29/AD0.2/CAP0.3/MAT0.314
P0.30/AD0.3/EINT3/CAP0.015
V323
RST57
VREF63
VSS6
VSSA59
P1.16/TRACEPKT016
P1.17/TRACEPKT112
P1.18/TRACEPKT28
P1.19/TRACEPKT34
P1.20/TRACESYNC48
P1.21/PIPESTAT044
P1.22/PIPESTAT140
P1.23/PIPESTAT236
P1.24/TRACECLK32
P1.25/EXTIN028
P1.26/RTCK24
P1.27/TDO64
P1.28/TDI60
P1.29/TCK56
P1.30/TMS52
P1.31/TRST20
V343
V351
VSS18
VSS25
VSS42
VSS50
RTXC13
RTXC25
V3A7
VBAT49
P0.3117
P0.26/AD0.510
U1
LPC2138
+3.3V
12
X1
C1
33pF
C2
33pF
12
X2
C3
22pF
C4
22pF
R11K
C5100pF
+3.3V
Xmodem, Ymodem, Zmodem
VT52, VT100, ANSIRXD
RTS
TXD
CTS
T1IN11
R1OUT12
T2IN10
R2OUT9
T1OUT14
R1IN13
T2OUT7
R2IN8
C2+
4
C2-
5
C1+
1
C1-
3
VS+2
VS-6
U2
MAX232
C6
1uF
C7
1uF
C81uF
C91uF
LOAD-1
LED-YELLOW
LOAD-2
LED-YELLOW
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