/********************************************************************* * * SPI to MCP4822 dual channel 12-bit DAC * ********************************************************************* * Bruce Land Cornell University * Spet 2015 *~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ #include #include #include // need for pps // Configuration Bit settings // SYSCLK = 40 MHz (8MHz Crystal/ FPLLIDIV * FPLLMUL / FPLLODIV) // PBCLK = 40 MHz // Primary Osc w/PLL (XT+,HS+,EC+PLL) // WDT OFF // Other options are don't care // 8MHZ 4MHz 80MHz 40 <--- 40MHz #pragma config FNOSC = FRCPLL, POSCMOD = OFF, FPLLIDIV = DIV_2, FPLLMUL = MUL_20, FPBDIV = DIV_1, FPLLODIV = DIV_2 #pragma config FWDTEN = OFF #pragma config FSOSCEN = OFF, JTAGEN = OFF, DEBUG = OFF // core frequency we're running at // peripherals at 40 MHz #define SYS_FREQ 40000000 #define I2C_CLOCK_FREQ 100000 #define I2C 1 #define GPIO 1 #define SPI 0 //can help regardless /* ====== MCP4822 control word ============== bit 15 A/B: DACA or DACB Selection bit 1 = Write to DACB 0 = Write to DACA bit 14 ? Don?t Care bit 13 GA: Output Gain Selection bit 1 = 1x (VOUT = VREF * D/4096) 0 = 2x (VOUT = 2 * VREF * D/4096), where internal VREF = 2.048V. bit 12 SHDN: Output Shutdown Control bit 1 = Active mode operation. VOUT is available. ? 0 = Shutdown the selected DAC channel. Analog output is not available at the channel that was shut down. VOUT pin is connected to 500 k???typical)? bit 11-0 D11:D0: DAC Input Data bits. Bit x is ignored. */ // A-channel, 1x, active #define DAC_config_chan_A 0b0011000000000000 //== Timer 2 interrupt handler =========================================== volatile unsigned int DAC_data ;// output value volatile unsigned char count = 0; volatile SpiChannel spiChn = SPI_CHANNEL2 ; // the SPI channel to use volatile int spiClkDiv = 16 ; // 20 MHz max speed for this DAC void __ISR(_TIMER_2_VECTOR, ipl2) Timer2Handler(void) { mT2ClearIntFlag(); // generate ramp DAC_data = (DAC_data + 1) & 0xfff ; // for testing // CS low to start transaction mPORTBClearBits(BIT_4); // start transaction //mPORTBClearBits(BIT_0); // test for ready while (TxBufFullSPI2()); // write to spi2 //WriteSPI2(DAC_config_chan_A | DAC_data); WriteSPI2(count++); // test for done while (SPI2STATbits.SPIBUSY); // wait for end of transaction // CS high //mPORTBSetBits(BIT_0); // end transaction mPORTBSetBits(BIT_4); } // ======================================================================== int main(void) { // Configure the device for maximum performance but do not change the PBDIV // Given the options, this function will change the flash wait states, RAM // wait state and enable prefetch cache but will not change the PBDIV. // The PBDIV value is already set via the pragma FPBDIV option above.. SYSTEMConfig(SYS_FREQ, SYS_CFG_WAIT_STATES | SYS_CFG_PCACHE); // timer interrupt ////////////////////////// // Set up timer2 on, interrupts, internal clock, prescalar 1, toggle rate // at 30 MHz PB clock 60 counts is two microsec // 400 is 100 ksamples/sec // 2000 is 20 ksamp/sec OpenTimer2(T2_ON | T2_SOURCE_INT | T2_PS_1_1, 400*5); // set up the timer interrupt with a priority of 2 ConfigIntTimer2(T2_INT_ON | T2_INT_PRIOR_2); mT2ClearIntFlag(); // and clear the interrupt flag // SCK2 is pin 26 // SDO2 (MOSI) is in PPS output group 2, could be connected to RB5 which is pin 14 PPSOutput(2, RPB5, SDO2); // control CS for DAC //mPORTBSetPinsDigitalOut(BIT_0); //mPORTBSetBits(BIT_0); mPORTBSetPinsDigitalOut(BIT_4); mPORTBSetBits(BIT_4); //setup up GPIO pin for toggling (need 4 pins_) //using RB0, RB1, RB8,R9 mPORTBSetPinsDigitalOut(BIT_0); mPORTBSetPinsDigitalOut(BIT_1); mPORTBSetPinsDigitalOut(BIT_8); mPORTBSetPinsDigitalOut(BIT_9); //I2C bit bang mPORTBSetPinsDigitalOut(BIT_2); mPORTBSetPinsDigitalOut(BIT_3); //set them both high for idle mPORTBSetBits(BIT_2);//SDA mPORTBSetBits(BIT_3);//SCL int start = 0; // // divide Fpb by 2, configure the I/O ports. Not using SS in this example // 16 bit transfer CKP=1 CKE=1 // possibles SPI_OPEN_CKP_HIGH; SPI_OPEN_SMP_END; SPI_OPEN_CKE_REV // For any given peripherial, you will need to match these SpiChnOpen(spiChn, SPI_OPEN_ON | SPI_OPEN_MODE8 | SPI_OPEN_MSTEN | SPI_OPEN_CKE_REV , spiClkDiv); UINT8 i2cData[10]; I2C_7_BIT_ADDRESS SlaveAddress; int Index; int DataSz; UINT32 actualClock; BOOL Acknowledged; BOOL Success = TRUE; UINT8 i2cbyte; // Initialize debug messages (when supported) //DBINIT(); // Set the I2C baudrate //actualClock = I2CSetFrequency(I2C2, SYS_FREQ, I2C_CLOCK_FREQ); //if ( abs(actualClock-I2C_CLOCK_FREQ) > I2C_CLOCK_FREQ/10 ) // { // DBPRINTF("Error: I2C1 clock frequency (%u) error exceeds 10%%.\n", (unsigned)actualClock); //} // Enable the I2C bus //I2CEnable(I2C2, TRUE); // setup system wide interrupts /// INTEnableSystemMultiVectoredInt(); int count0 = 0; int flag0 = 0; int count1 = 0; int flag1 = 0; mPORTBClearBits(BIT_0); mPORTBClearBits(BIT_1); mPORTBClearBits(BIT_8); mPORTBClearBits(BIT_9); while(1) { // toggle a bit for ISR perfromance measure //mPORTBToggleBits(BIT_1); //Julia: toggle bit for gpio stuff if(GPIO==1){ if(count0 == 1200 && flag0 == 0){ mPORTBSetBits(BIT_0); count0 = 0; flag0 = 1; } if(count0 == 800 && flag0 ==1){ mPORTBClearBits(BIT_0); flag0 = 0; } if(count0 == 750){ mPORTBToggleBits(BIT_1); } if(count1 == 500 && flag1 == 0){ mPORTBSetBits(BIT_8); mPORTBClearBits(BIT_9); count1 = 0; flag1 = 1; } if(count1 == 1000 && flag1 ==1){ mPORTBClearBits(BIT_8); mPORTBSetBits(BIT_9); count1 = 0; flag1 = 0; } count0 = count0+1; count1 = count1+1; } if(I2C==1){ //delay(10); // make a for loop //start command if(start==0) { int z; for(z=0; z<10000; z++){ // :) } mPORTBClearBits(BIT_2); int a; for(a=0; a<1000; a++){ // :) } mPORTBClearBits(BIT_3); start = 1; int b; for( b=0; b<1000; b++){ // :) } }else{ //toggle scl mPORTBSetBits(BIT_2); //send the data out int c; for(c = 0; c<8; c++){ mPORTBClearBits(BIT_3); int d; for(d=0; d<1000; d++){ // :) } mPORTBSetBits(BIT_3); int e; for(e=0; e<1000; e++){ // :) } mPORTBSetBits(BIT_2); } //ack/nack mPORTBClearBits(BIT_3); mPORTBClearBits(BIT_2); int f; for(f=0; f<1000; f++){ // :) } mPORTBSetBits(BIT_2); int g; for(g=0; g<1000; g++){ // :) } //stop condition mPORTBSetBits(BIT_3); int h; for(h=0; h<1000; h++){ // :) } mPORTBClearBits(BIT_3); mPORTBClearBits(BIT_2); int i; for( i=0; i<1000; i++){ // :) } mPORTBSetBits(BIT_3); mPORTBSetBits(BIT_2); start = 0; } } } }