ARM LPC2129 Mini Development Board – POT Interfacing (ADC)
The “ARM LPC2129 Mini Development Board – POT Interfacing (ADC)” wiki discussed here is in reference to the rhydoLABZ make LPC2129 Development Board-Mini, however it makes no difference even if the board used is either LPC2138 Development Board-Mini or LPC2148 Development Board-Mini.i.e, this interfacing guide is common for LPC2129/LPC2138/LPC2148 Mini Development Boards from rhydoLABZ.ARM LPC2129 Mini Development Board has two 10-bit successive approximation ADCs, as per the controller specification. ADC0 has 6 channels & ADC1 has 8 channels. The maximum possible input to ADC is 3.3V, which gives output reading as 1023 (The maximum value that can be represented if result is taken in 10 bits), thus the resolution is 3.3V/1024=3.22 mV. The development board has an SMD POT connected to pin P0.29 i.e, AD0.2 via jumper J12. On varying the POT, voltage input on the ADC pin P0.29 varies between 0 – 3.3V
Schematic:
Sample code to check the ADC module of LPC2129 using the on board SMD pot is given below. The output is displayed on LCD and the variation can be checked by varying the POT. While checking the ADC never forget to short jumper J12, leaving it open disconnects the POT from port pin P0.29 and it can be used for any other desired purpose.
Sample code:
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/******************************************************************************** HEADER FILES *********************************************************************************/ #include<lpc21xx.h> #define RS 0x00020000 /* RS - P1.17 */ #define RW 0X00040000 /* R/W - P1.18 */ #define EN 0X00080000 /* E - P1.19 */ #define CLR 0X00FE0000 /******************************************************************************** VARIABLE DECLARATION *********************************************************************************/ unsigned int adc_value=0; /******************************************************************************** * Function : Delay * * * * Description : Function for Delay * * * * Parameters : x - Delay time * *********************************************************************************/ int Delay(unsigned int x) { x=x*12000; while(x!=0) { x--; } return 0; } /******************************************************************************** * Function : LCD_Command * * * * Description : Function to give command to LCD * * * * Parameters : command - command * *********************************************************************************/ void LCD_Command(char command) { int Temp; IO1CLR = CLR; /* Clearing the port pins */ IO1SET = EN; /* Enable pin high */ IO1CLR = RS; /* RS=0 for command register */ IO1CLR = RW; /* R/W=0 for write */ Temp = (command & 0xF0) << 16; /* Taking the first nibble of command */ IO1SET = IO1SET | Temp; /* Writing it to data line */ Delay(2); IO1CLR = EN; /* Enable pin low to give H-L pulse */ } /******************************************************************************** * Function : LCD_Command1 * * * * Description : Function to give command to LCD * * * * Parameters : command1 - command * *********************************************************************************/ void LCD_Command1(char command1) { int Temp; IO1CLR = CLR; /* Clearing the port pins */ IO1SET = EN; /* Enable pin high */ IO1CLR = RS; /* RS=0 for command register */ IO1CLR = RW; /* R/W=0 for write */ Temp = (command1 & 0xF0) << 16; /* Taking the first nibble of command */ IO1SET = IO1SET | Temp; /* Writing it to data line */ Delay(2); IO1CLR = EN; /* Enable pin low to give H-L pulse */ IO1CLR = CLR; /* Clearing the port pins */ IO1SET = EN; /* Enable pin high */ IO1CLR = RS; /* RS=0 for command register */ IO1CLR = RW; /* R/W=0 for write */ Temp = (command1 & 0x0F) << 20; /* Taking the second nibble of command */ IO1SET = IO1SET | Temp; /* Writing it to data line */ Delay(2); IO1CLR = EN; /* Enable pin low to give H-L pulse */ } /******************************************************************************** * Function : LCD_Data * * * * Description : Function to give data for displayto LCD * * * * Parameters : data - data * *********************************************************************************/ void LCD_Data(char data) { int Temp; IO1CLR = CLR; /* Clearing the port pins */ IO1SET = EN; /* Enable pin high */ IO1SET = RS; /* RS=1 for data register */ IO1CLR = RW; /* R/W=0 for write */ Temp = (data & 0xF0) << 16; /* Taking the first nibble of command */ IO1SET = IO1SET | Temp; /* Writing it to data line */ Delay(2); IO1CLR = EN; /* Enable pin low to give H-L pulse */ IO1CLR = CLR; /* Clearing the port pins */ IO1SET = EN; /* Enable pin high */ IO1SET = RS; /* RS=1 for data register */ IO1CLR = RW; /* R/W=0 for write */ Temp = (data & 0x0F)<<20; /* Taking the second nibble of command */ IO1SET = IO1SET | Temp; /* Writing it to data line */ Delay(2); IO1CLR = EN; /* Enable pin low to give H-L pulse */ } /******************************************************************************** * Function : LCD_String * * * * Description : Function to display string on LCD * * * * Parameters : String to be displayed * *********************************************************************************/ void LCD_String(unsigned char *dat) { while(*dat!='\0') /* Check for termination character */ { LCD_Data(*dat); /* Display the character on LCD */ dat++; /* Increment the pointer */ } } /******************************************************************************** * Function : LCD_Init * * * * Description : Function to initialise LCD * * * * Parameters : None * *********************************************************************************/ void LCD_Init(void) { Delay(15); LCD_Command(0x30); Delay(10); LCD_Command(0x30); Delay(5); LCD_Command(0x30); LCD_Command(0x20); LCD_Command1(0x28); LCD_Command1(0x01); /* Clear display */ LCD_Command1(0x06); /* Auto increment */ LCD_Command1(0x0C); /* Cursor off */ } /******************************************************************************** * Function : ADC_Conversion * * * * Description : Function to get ADC reading * * * * Parameters : None * *********************************************************************************/ int ADC_Conversion() { int ab; /* Variable to store ADC value */ Delay(1); ADCR = ADCR|0x01000000; /* Start conversion */ while((ADDR&0x80000000)!=0x80000000); /* Wait here till conversion is over */ ab = (ADDR&0x0000FFC0); /* Extracting the result */ ab = (ab>>6); /* Shift 6 bits right */ return ab; /* Return the result */ } /******************************************************************************** * Function : Int_ASCII * * * * Description : Function to store integer value in array * * * * Parameters : value - value to be stored * * cnt - no: of digits * *********************************************************************************/ void Int_ASCII(int value,char cnt) { int i = 0; /* Local variables */ char array[7]; int values; values= value; for(i=1;i<=cnt;i++) /* Store the received value in array */ { array[i] = values%10; values = values/10; } for(i=cnt;i>=1;i--) /* Display it on LCD */ { LCD_Data(array[i]+'0'); } } /******************************************************************************** * Function : ADC_Check * * * * Description : Function to take ADC reading & display it on LCD * * * * Parameters : None * *********************************************************************************/ void ADC_Check() { ADCR=0x00200604; /* PDN=1,CLKDIV=6,channel=AD0.2 */ LCD_Command1(0x80); LCD_String("ADC Checking...."); LCD_Command1(0xC0); LCD_String("ADC:"); adc_value=ADC_Conversion(); /* Get the result of conversion */ LCD_Command1(0xC4); /* 2nd row, 5th location */ Int_ASCII(adc_value,4); /* Display the result on LCD */ Delay(100); } /******************************************************************************** * Function : PORT_Initial * * * * Description : Function for PORT Initialisation * * * * Parameters : None * *********************************************************************************/ void PORT_Initial(void) { IO1DIR = 0x00FE0000; /* LCD pins set as o/p */ PINSEL0 = 0x00000000; PINSEL1 = 0x05000000; /* ADC function for 0.28 & 0.29 */ PINSEL2 = 0x00000000; } /******************************************************************************** MAIN FUNCTION *********************************************************************************/ int main() { PORT_Initial(); /* Initialise the ports */ LCD_Init(); /* Initialise LCD */ LCD_String("Rhydo Technology"); LCD_Command1(0xC0); /* 2nd row, 1st location */ LCD_String(" Cochin "); LCD_Command1(0x80); /* 1st row, 1st location */ LCD_String("ADC Checking."); LCD_Command1(0x01); /* Clear screen */ while(1) { ADC_Check(); /* Take ADC reading */ } } |
Once the above code is loaded on to the controller, it starts reading the POT values and the same will be displayed on the LCD module as shown in the image below.
Topics related to ARM LPC2129 Mini Development Board:
- ARM LPC2129 Mini Development Board – Overview
- ARM LPC2129 Mini Development Board – LED Interfacing
- ARM LPC2129 Mini Development Board – LCD Interfacing
- ARM LPC2129 Mini Development Board – UART0 Interfacing
- ARM LPC2129 Mini Development Board – UART1 Interfacing
- ARM LPC2129 Mini Development Board – Switches Interfacing
- ARM LPC2129 Mini Development Board – BUZZER Interfacing
- ARM LPC2129 Mini Development Board – POT Interfacing (ADC)
- ARM LPC2129 Mini Development Board – Temperature Sensor Interfacing(ADC)
- ARM LPC2129 Mini Development Board – Interfacing Servo motor
- ARM LPC2129 Mini Development Board – CAN Interfacing
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- Datasheets
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- Click here to buy rhydoLABZ ARM LPC2138 Mini Development Board
- Click here to buy rhydoLABZ ARM LPC2148 Mini Development Board
- Click here to buy rhydoLABZ ARM LPC2129 Mini Development Board
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