/* * File: * DMA glue logic timer2-to-ADC-to-memory * * --------- * Bruce Land * Target PIC: PIC32MX250F128B */ // all peripheral library includes #define _SUPPRESS_PLIB_WARNING #include // serial interface #include // sine function #include ///////////////////////////////////////////////////////// #pragma config FNOSC = FRCPLL, POSCMOD = OFF //#pragma config FNOSC = PRIPLL, POSCMOD = EC, OSCIOFNC = OFF #pragma config FPLLIDIV = DIV_2, FPLLMUL = MUL_20, FPLLODIV = DIV_2 //40 MHz #pragma config FPBDIV = DIV_1 // PB 40 MHz // turn off alternative functions for port pins B.4 and B.5 #pragma config JTAGEN = OFF, DEBUG = OFF #pragma config FSOSCEN = OFF // ============== // SPI DAC: A-channel, 1x, active #define DAC_config_chan_A 0b0011000000000000 // ============== //clearing bit 1 starts ADC (write to AD1CON1CLR) char start_ADC = 0b00000010 ; //AD1CON1CLR mask // array to hold DMA output from ADC short v_in[256]; // SPI transport source short DAC_data; // === Main ====================================================== void main(void) { SYSTEMConfig(40000000, SYS_CFG_WAIT_STATES | SYS_CFG_PCACHE); /* Blocks: * block 0 -- wait for timer2 then trigger ADC, MANUALLY by DMA copy * block 1 -- wait for ADC done copy 256 conversions to memory */ // === DMA ===================== // DMA0 writes ADC start bit on timer2-match flag //-- writing a zero to SAMP bit ends sampling and starts conversion //-- writing to the AD1CON1CLR register clears the bit mask stored in start_ADC //-- AD1CON1CLR is one of three write-only shadow registers to AD1CON1 (SET, CLR, INV) //-- The ADC setup below sets AUTOSAMPLE ON, so SAMP bit is auto-set at end of conversion // DMA0 is in AUTO mode to keep repeating whenver there is a timer event DmaChnOpen(0, 0, DMA_OPEN_AUTO); DmaChnSetTxfer(0, &start_ADC, (void*)&AD1CON1CLR, 1, 1, 1); DmaChnSetEventControl(0, DMA_EV_START_IRQ(_TIMER_2_IRQ)); DmaChnEnable(0); // DMA0 execute interval source // slow enough to test using potentiometer input to ADC OpenTimer2(T2_ON | T2_SOURCE_INT | T2_PS_1_8, 40000); // // DMA1 writes ADC to memory on ADC-complete flag // Transfers 256 shorts for every ENABLE from main // DMA1 is opened in DEFAULT mode so that MAIN can start and sync with DMA DmaChnOpen(1, 0, DMA_OPEN_DEFAULT); DmaChnSetTxfer(1, (void*)&ADC1BUF0, (void*)v_in, 2, 512, 2); //256 16-bit integers); DmaChnSetEventControl(1, DMA_EV_START_IRQ(_ADC_IRQ)); // === set up i/o port pins ============= ANSELA =0; // turn off analog on A ANSELB =0; // turn off analog on B // === led ======= mPORTASetBits(BIT_0); mPORTASetPinsDigitalOut(BIT_0); // === init the uart2 =================== // to show test results // The RX pin must be one of the Group 2 input pins // RPA1, RPB1, RPB5, RPB8, RPB11 PPSInput (2, U2RX, RPA1); //Assign U2RX to pin RPA1 -- // The TX pin must be one of the Group 4 output pins // RPA3, RPB0, RPB9, RPB10, RPB14 PPSOutput(4, RPB10, U2TX); //Assign U2TX to pin RPB10 -- #define BAUDRATE 115200 UARTConfigure(UART2, UART_ENABLE_PINS_TX_RX_ONLY); UARTSetLineControl(UART2, UART_DATA_SIZE_8_BITS | UART_PARITY_NONE | UART_STOP_BITS_1); UARTSetDataRate(UART2, 40000000, BAUDRATE); UARTEnable(UART2, UART_ENABLE_FLAGS(UART_PERIPHERAL | UART_RX | UART_TX)); // === DAC SPI =============== // open the SPI channel // clk divider set to 4 for 10 MHz SpiChnOpen(SPI_CHANNEL2, SPI_OPEN_ON | SPI_OPEN_MODE16 | SPI_OPEN_MSTEN | SPI_OPEN_CKE_REV , 4); // SDO2 (MOSI) is in PPS output group 2, could be connected to RB5 which is pin 14 PPSOutput(2, RPB5, SDO2); mPORTBSetBits(BIT_4); // Set SPI chip select mPORTBSetPinsDigitalOut(BIT_4); //Set B port as output // ADC setup =================================================================== // trigger on timer3 match CloseADC10(); // ensure the ADC is off before setting the configuration // define setup parameters for OpenADC10 // Turn module on | ouput in integer | trigger mode auto | enable autosample // ADC_CLK_AUTO -- Internal counter ends sampling and starts conversion (Auto convert) // ADC_CLK_TMR -- triggered off T3 // ADC_CLK_MANUAL -- triggered by clearing SAMP bit in AD1CON1 // ADC_AUTO_SAMPLING_ON -- Sampling begins immediately after last conversion completes; SAMP bit is automatically set // ADC_AUTO_SAMPLING_OFF -- Sampling begins with AcquireADC10(); // ADC_FORMAT_FRACT16 -- 10 bits aligned so top bit is bit-15 // ADC_FORMAT_INTG16 -- 10 bits allgned so top bit is bit-9 #define PARAM1 ADC_AUTO_SAMPLING_ON | ADC_CLK_MANUAL | ADC_FORMAT_FRACT16 // define setup parameters for OpenADC10 // ADC ref external | disable offset test | disable scan mode | do 1 sample | use single buf | alternate mode off #define PARAM2 ADC_VREF_AVDD_AVSS | ADC_OFFSET_CAL_DISABLE | ADC_SCAN_OFF | ADC_SAMPLES_PER_INT_1 | ADC_ALT_BUF_OFF | ADC_ALT_INPUT_OFF // // Define setup parameters for OpenADC10 // use peripherial bus clock | set sample time | set ADC clock divider // ADC_CONV_CLK_Tcy2 means divide CLK_PB by 2 (max speed) // ADC_SAMPLE_TIME_5 seems to work with a source resistance < 1kohm // At PB clock 30 MHz, divide by two for ADC_CONV_CLK gives 66 nSec #define PARAM3 ADC_CONV_CLK_PB | ADC_SAMPLE_TIME_5 | ADC_CONV_CLK_Tcy2 //ADC_SAMPLE_TIME_15| ADC_CONV_CLK_Tcy2 // define setup parameters for OpenADC10 // set AN0 and as analog inputs #define PARAM4 ENABLE_AN11_ANA // define setup parameters for OpenADC10 // do not assign channels to scan #define PARAM5 SKIP_SCAN_ALL // use ground as neg ref for A | use AN0 for input A // configure to sample AN4 SetChanADC10( ADC_CH0_NEG_SAMPLEA_NVREF | ADC_CH0_POS_SAMPLEA_AN11 ); // configure to sample AN0 OpenADC10( PARAM1, PARAM2, PARAM3, PARAM4, PARAM5 ); // configure ADC using the parameters defined above EnableADC10(); // Enable the ADC // === MAIN loop ==================== // mark start for debugging printf( "Start:\n\r"); while(1){ // enable the DMA to memory after the SPI transfer (below) is complete DmaChnEnable(1); // heartbeat LED for debugging mPORTAToggleBits(BIT_0); // ADC transfer done // waits for DMA1 to become un-enabled at end of memory transfer #define Chn_busy 0x80 while( (DCH1CON & Chn_busy) ){}; // print for testing printf("%d \n\r", v_in[0]); // write 256 values to spi2 int i; for(i=0; i<256; i++) { // CS low to start transaction mPORTBClearBits(BIT_4); // start transaction // initiate SPI transfer (assumes 16-bit fractional ADC format) DAC_data = v_in[i]>>4; WriteSPI2(DAC_config_chan_A | DAC_data); // test for done while (SPI2STATbits.SPIBUSY){}; // wait for end of transaction // CS high mPORTBSetBits(BIT_4); // end transaction } } // while(1) } // main // === end ======================================================