Scans through the DAC values, and copies a set of ADC values to file on USB local filesystem. Reads from the ADC directly. Connect pin 18 to pin 17.
main.cpp
- Committer:
- Mischa
- Date:
- 2010-12-14
- Revision:
- 0:caf407d467b1
File content as of revision 0:caf407d467b1:
// Scans through the D/A converter values, and copies a set of A/D converter values to file on USB local filesystem. // Connect pin 18 to pin 17. #include "mbed.h" AnalogOut aout(p18); LocalFileSystem local("local"); // Create the local filesystem under the name "local" const int N = 100; //number of samples per D/A value int i; int n; unsigned short x[N]; short trim = 3; // ADC trim; appears this is added to the ADC readings in two's complement (i.e, -8 gives results in too low readings, 0 gives about correct readings, +3 gives really correct readings for my system, and +7 gives too high readings.) // /4 /26 -> mbed // /8 /3 -> nice // /1 /8 -> 12MHz (max) (ugly) // /1 /12 (i.e., 11 in reg.) -> nice int main() { // A/D power on, set A/D clk divider /4 LPC_SC->PCONP |= (1 << 12); // power on, PCADC bit LPC_SC->PCLKSEL0 &= ~(0x1 << 24); // PCLK_ADC=0,1,2,3 -> CCLK /4,/1,/2,/8 // software-controlled ADC settings LPC_ADC->ADCR = (0 << 0) // SEL: 0 = no channels selected yet | (11 << 8) // CLKDIV: PCLK_ADC0 is divided by this number+1 (8 bits) | (0 << 16) // BURST: 0 = software control | (1 << 21) // PDN: 1 = operational | (0 << 24); // START: 0 = no start //p15 = LPC1768 pin 9 = P0.23 = AD0.0 = PINSEL1 bit 15&14 01 //p16 = LPC1768 pin 8 = P0.24 = AD0.1 = PINSEL1 bit 17&16 01 //p17 = LPC1768 pin 7 = P0.25 = AD0.2 = PINSEL1 bit 19&18 01 //p19 = LPC1768 pin 21 = P1.30 = AD0.4 = PINSEL3 bit 29&28 11 //p20 = LPC1768 pin 20 = P1.31 = AD0.5 = PINSEL3 bit 31&30 11 //Same bits in PINMODEi, set these to 10 to disconnect pull up/pull down resistors LPC_PINCON->PINSEL1 &= ~((unsigned int)0x3 << 18); LPC_PINCON->PINSEL1 |= (unsigned int)0x1 << 18; LPC_PINCON->PINMODE1 &= ~((unsigned int)0x3 << 18); LPC_PINCON->PINMODE1 |= (unsigned int)0x2 << 18; // neither pull up nor pull down LPC_ADC->ADCR &= ~0xFF; LPC_ADC->ADCR |= 1 << 2; // ADC0[2] /* LPC_PINCON->PINSEL3 &= ~((unsigned int)0x3 << 28); LPC_PINCON->PINSEL3 |= (unsigned int)0x3 << 28; LPC_PINCON->PINMODE3 &= ~((unsigned int)0x3 << 28); LPC_PINCON->PINMODE3 |= (unsigned int)0x2 << 28; // neither pull up nor pull down LPC_ADC->ADCR &= ~0xFF; LPC_ADC->ADCR |= 1 << 4; // ADC0[4] */ LPC_ADC->ADTRM&=~0x00F0; LPC_ADC->ADTRM|=(trim<<4) & 0x00F0; //set the trim FILE *fp = fopen("/local/out.txt", "w"); // Open "out.txt" on the local file system for writing for (i=0;i<1024;i++) { aout.write_u16(i<<6); wait(0.000100); for (n=0;n<N;n++) { // Select channel and start conversion LPC_ADC->ADCR |= 1 << 24; // Repeatedly get the sample data until DONE or OVERRUN bit unsigned int data; do { data = LPC_ADC->ADGDR; } while ((data & ((unsigned int)3 << 30)) == 0); x[n]=data; } // Stop conversions LPC_ADC->ADCR &= ~(1 << 24); fwrite(x,sizeof(x[0]),sizeof(x)/sizeof(x[0]),fp); } fclose(fp); }