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| Fig 1 7 Segment LED Display |
0 – 99 7 Segment(SSD) Counter on LPC2148 ARM7 Development Board
What is 7 Segment Display(SSD)? – A seven-segment display is a form of electronic display device for displaying decimal numbers (and some alphabets too). 7-segment displays are simply 7 LEDs placed in one same package. To change the displayed value, we simply turn on or off different combinations of LEDs.
Types of 7 Segment : – There are two types of 7-segment displays: Common Anode(CA) and Common Cathode(CC). In common anode displays, the anode of the LEDs are connected to one pin (usually connected to a power source). In common cathode displays, the cathodes are connected to one pin (usually connected to ground).
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| Fig 2 Common Anode and Common Cathode Diagram Representation |
This code is tested in Keil uVision 4. Developed for ARM LPC2148 kit of ALS Advanced Systems Board.
There are two multiplexed 7-segment displays LT543 (U8 and U9) on the board.
Seg_A connected to P0.16
Seg_B connected to P0.17
Seg_C connected to P0.18
Seg_D connected to P0.19
Seg_E connected to P0.20
Seg_F connected to P0.21
Seg_G connected to P0.22
Seg_DP connected to P0.23
Common cathode of U8 –> P0.28
Common cathode of U9 –> P0.29
Values to be sent to the Ports:
In following table, we convert 8 pin’s 8 bit binary data into hex code and this data is sent to ports.
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| Fig 3 7 Segment Hex Numbers |
ARM Code :
;/*Program to Count 0-99 on 7 Segment ARM LPC2148*/
#include<LPC214x.h>
int main()
{
int segData[16] = {
0x003F0000,// 0
0x000
60000,// 1
0x005B0000,// 2
0x004F0000,// 3
0x00660000,// 4
0x006D0000,// 5
0x007D0000,// 6
0x00070000,// 7
0x007F0000,// 8
0x006F0000,// 9
0x00770000,// A
0x007C0000,// B
0x00390000,// C
0x005E0000,// D
0x00790000,// E
0x00710000 //F
};
int i = 0,j = 0,k = 0,Count = 9;
PINSEL0 = 0x00000000;
IODIR0 = 0x30FF0000;
IOSET0 = 0x30FF0000;
while(1)
{
for(i = 0; i<=Count; i++)
{
for(j = 0; j<=Count; j++)
{
for(k = 0; k<=200000 ; k++)
{
IOCLR0 = 0x10FF0000;
IOSET0 = segData[j];
IOSET0 = 0x10FF0000;
IOCLR0 = 0x20FF0000;
IOSET0 = segData[i];
IOSET0 = 0x20FF0000;
}
}
}
}
}
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