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| − | [[category: ARM Tutorials]] | + | #REDIRECT [[LPC1768: ADC Programming]] |
| − | [[User:Amruta|Amruta]] ([[User talk:Amruta|talk]]) 13:28, 17 March 2015 (IST)
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| − | ----
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| − | =Basics=
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| − | LPC1768 has 12 bit ADC which is multiplexed among 8 input pins. It's measurement range is typically 3V which means that ADC resolution is approximately 0.7 mV.
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| − | | + | |
| − | ===Registers===
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| − | Here we will discuss commonly used ADC registers.
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| − | =====ADCR ( ADC Control Register )=====
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| − | {| class="wikitable" style="text-align:center; background-color:#ABCDEF;margin: 1em auto 1em auto"
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| − | !colspan = '9'|ADCR
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| − | |-
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| − | |31:28|| 27 || 26:24|| 23:22 || 21 || 20:17 || 16|| 15:8 || 7:0
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| − | |-
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| − | |Reserved||EDGE||START||Reserved|| PDN || Reserved || BURST || CLCKDIV || SEL
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| − | |}
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| − | '''Bit 7:0 – SEL : Channel Select'''
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| − | These bits select which of the AD0.7:0 pins is (are) to be sampled and converted. There is one bit per channel e. g. bit o for AD0, bit 7 AD7.
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| − | Write one to enable respective channel. All zeroes is equivalent to 0x01.
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| − | '''Bit 15:8 – CLCKDIV : Clock Divisor'''
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| − | The APB clock (PCLK_ADC0) is divided by (this value plus one) to produce the clock for the A/D converter, which should be less than or equal to 13 MHz.
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| − | '''Bit 16 – BURST'''
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| − | Repeated conversions can be terminated by clearing this bit.
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| − | | + | |
| − | '''Bit 21 – PDN : Power Down Mode'''
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| − | Setting this bit brings ADC out of power down mode and makes it operational.
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| − | '''Bit 24:26 – START'''
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| − | When the BURST bit is 0, these bits control whether and when an A/D conversion is started:
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| − | {| class="wikitable" style="text-align:center; background-color:#C0C0C0;"
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| − | !Bit Value || FIFO Status
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| − | |-
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| − | |0|| Empty
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| − | |-
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| − | |1|| Not Empty
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| − | |-
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| − | |}
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| − | | + | |
| − | =====ADGDR ( ADC Global Data Register )=====
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| − | {| class="wikitable" style="text-align:center; background-color:#ABCDEF;margin: 1em auto 1em auto"
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| − | !colspan = '9'|ADCR
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| − | |-
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| − | |31|| 27 || 26:24|| 23:16|| 15:4 || 3:0
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| − | |-
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| − | |Done||EDGE||Channel || Reserved || RESULT|| Reserved
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| − | |}
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| − | =Schematic=
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| − | =Code=
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| − | <syntaxhighlight>
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| − | /*-----------------------------------------------------------------------------
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| − | note : Refer adc.h to enable ADC channels.
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| − | ------------------------------------------------------------------------------*/
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| − | #include "lpc17xx.h" //device specific heaader file
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| − | #include "uart.h" //Explore Embedded UART library which conatins the lcd routines
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| − | #include "adc.h" //Explore Embedded ADC library which conatins the adc routines
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| − | /* start the main program */
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| − | int main()
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| − | {
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| − | uint16_t adc_result;
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| − | | + | |
| − | /* Setup and initialize the microcontroller system */
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| − | SystemInit();
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| − | /* Initialize the UART before displaying any thing on the lcd */
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| − | UART_Init(UART0,9600);
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| − | /* Initialize the adc before starting the conversion */
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| − | ADC_Init();
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| − | /* Display "ADC Channel zero" on first line*/
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| − | UART_Printf("ADC Channel zero");
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| − | /* Display the adc channel zero value continously */
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| − | while(1)
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| − | {
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| − | /*Get the adc value of channel five */
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| − | adc_result= ADC_GetAdcValue(5);
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| − |
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| − | /*Display the adc value on UART*/
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| − | UART_Printf("\n %u",adc_result);
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| − | }
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| − | }
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| − | | + | |
| − | </syntaxhighlight>
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| − | {{DISQUS}}
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