4. PIN Configuration (Cont..)
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LPC2148
PORT 0 PORT 1
P0.0 to P0.15 , P0.16 to P0.31 P1.0 to P1.15 , P1.16 to P1.31
Fig : 2 Distribution of PORT’s and PIN’s
5. PORTx
PORT 0:
• P0.0 to P0.15 → Lower 16 bit Pins
• P0.17 to P0.31 → Higher 16 bit Pins
PORT 1:
• P1.0 to P1.15 → Lower 16 bit Pins
• P1.17 to P1.31 → Higher 16 bit Pins
PORT 0 – Lower 16 bit and higher 16 bit
are used as GPIO pins
PORT 1 – Only higher 16 bit pins are used
as GPIO pins.
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6. PORTx (Cont..)
• Pins of P1.0 to P1.15 of lower 16 bit pins
are not available for the user.
• Also P0.24, P0.26 and P0.27 are not
available for user.
• Out of 64 pins only user can use 45 Pins
of LPC2148.
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7. Configuring PIN’s
• To use the 45 pins we must configure the pins by
configuring the following registers.
• IOxPIN/IOPINx → IO pin Status register
• IODIRx → Direction register
• IOSETx → State set register
• IOCLRx → PIN Clear register
• All the registers are 32 bit registers each bit
controls the each pin of LPC2148.
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8. Configuring PIN’s
IOPINx – IO Pin Status register
Px.31 Px.27 Px.23 Px.19 Px.15 Px.11 Px.7 Px.3 Px.0
0000 0000 0000 0000 0000 0000 0000 0000
This can be written in the Hexa Decimal format
0 x 0 0 0 0 0 0 0 0
0x stands for hexa decimal deceleration
• Reading the values of pins can be done by
IOPINx
Ex: IOPIN0 = 0x0000000F
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9. Configuring PIN’s (Cont…)
IODIRx - Direction register
• Assigning 0 → will make pin as INPUT
• Assigning 1 → will make pin as OUTPUT
• By default the pin value will be set as ‘0’
• If we want to change the pin P0.0 to P0.3
as OUTPUT pins then declaration will be
Ex: 0 x 0 0 0 0 0 0 0 F
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10. Configuring PIN’s (Cont…)
IOSETx - State set register
Ex : 0 x 0 0 0 0 0 0 0 F // Px.0 to Px.3 as High
IOCLRx - PIN Clear register
Ex : 0 x 0 0 0 0 0 0 0 F // Px.0 to Px.3 satus will be
cleared
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11. Configuring PIN’s (Cont…)
S1 S0 O/P
0 0 GPIO
0 1 1st
1 0 2nd
1 1 3rd
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PSB
GPIO
Ist Alternate Function
2nd Alternate Function
Reserve
Px.y
S1 S0
x – 0 or 1
y – 0 to 31
Fig : 3 General Block Diagram of single
Table : 1 Selector Input and PIN State
S1 and S0 values are configured by associated register of PSB
12. Configuring PIN’s (Cont…)
• PSB – Pin Select Block has the following
registers
• PINSEL0 –Controls the pins from P0.0 to P0.15
• PINSEL1 –Controls the pins from P0.16 to P0.31
• PINSEL2 –Controls the pins from P1.16 to P1.31
• Each of the registers are 32 bit wide then how it
controls the 16 bit pins
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13. Configuring PIN’s (Cont…)
• Lets take the example of PINSEL0 32 bit register
which controls the pins from P0.0 to P0.15.
• Similarly the registers of PINSEL1 and PINSEL2
will be distributed to the remaining pins of
corresponding PORTs
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00
P0.12
00
P0.11
00
P0.10
00
P0.9
00
P0.8
00
P0.7
00
P0.6
00
P0.5
00
P0.4
00
P0.3
00
P0.2
00
P0.1
00
P0.0
S1 – S0S1 – S0
Fig : 4 Distribution of 32 bit registers to PINs of PORT 0
15. Configuring PIN’s (Cont…)
• Example for configuring P0.0 pin as a Tx Pin for
USART communication
• PINSEL0 = 0 x 0 0 0 0 0 0 0 1
P0.0 become as TxD0 by setting LSB values of P0.3
to P0.0 as 0001
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PSB
GPIO
TxDo
PWM
Reserve
P0.0
S1 S0
Fig : 5 Features of P0.0 pin
16. Simple LED Blinking Program
• Blink the LED connected in PORT1
# include <lpc21xx.h> // Include header file
void delay(void);
int main(void)
{
PINSEL2 = 0x00000000; // Configure P1.16 as GPIO pin
IODIR1 = 0x00000000; // Configure P1.16 as OUTPT pin
while(1) {
IOSET1 = 0x00010000; // Turn ON LED at P1.16
delay(); // Wait for a while
IOCLR1 = 0x00010000; // Turn OFF LED at P1.16
delay(); // Wait for a while
}
}
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17. Simple LED Blinking Program
void delay(void){
unsigned int j; // assign the variable j
for(j=0;j<1000000;j++) // Increment j till
} 1000000
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18. Assignment
• Draw the circuit for the above program
• Write the program for blinking the LED from
P0.16 to P0.23.
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