/** * Bruce Land and Hunter Adams (vha3@cornell.edu) * * HARDWARE CONNECTIONS * - GPIO 16 ---> VGA Hsync * - GPIO 17 ---> VGA Vsync * - GPIO 18 ---> 470 ohm resistor ---> VGA Green lo-bit to VGA green * - GPIO 19 ---> 330 ohm resistor ---> VGA Green hi_bit to VGA green * - GPIO 20 ---> 330 ohm resistor ---> VGA Blue * - GPIO 21 ---> 330 ohm resistor ---> VGA Red * - RP2040 GND ---> VGA GND * * RESOURCES USED * - PIO state machines 0, 1, and 2 on PIO instance 0 * - DMA channels 0, 1, 2, and 3 * - 153.6 kBytes of RAM (for pixel color data) * * Protothreads v1.1.1 * Serial console on GPIO 0 and 1 for debugging * and for synth conrol * * DAC : * GPIO 5 (pin 7) Chip select GPIO 6 (pin 9) SCK/spi0_sclk GPIO 7 (pin 10) MOSI/spi0_tx 3.3v (pin 36) -> VCC on DAC GND (pin 3) -> GND on DAC * * ===================================================== * * There are two threads running on each core, plus the synthesis ISR running on core1 * The PDE synthesis woks nicely with s15x16 fixed point, but fails with s1x14, probably * due to excessive runcation eror. * * ========== * Support routines: * -- ADC setup * -- Define two different fixed point schemes * One for DDS which requires bigger numbers, the other for FFT which needs fast execution. * -- Set up a low-level timer alarm which truggers the synthesis ISR * -- Define the FFT routine in 16-bit fixed point for speed * -- Define routine to extract a fast FFT magnutude specterum * Accuracy is about 2% * -- Define routine to extract a VERY low resoultion approximaton to log(mag) * The bit twiddling produces a u4x4 fixed poiint log. Good enough for graphics only. * * ========== * Core0: * * -- Graphics thread which generates some text, then currently does nothing * * * ========== * Core1: * * -- synthesis ISR triggered by a timer alarm * ---- runs at 40KHz (25 uSec interval) for audio synthesis. * ---- computes fulll string PDE * ---- Not reaaly practical, since max length of srin is 20 at 40 KHz. * ---- and take 0.6 of a cpu. * ---- Pushes output to an SPI channel * ---- Fills an array with DDS results for the FFT thread * * -- FFT thread which waits for a buffer full signal from the ISR, then draws spectra * ---- Does a 2048 point FFT then gets the amplitude of the frequency bins and takes a VERY approx log2 * ---- plots the amlitude spectrum, log amplitude spectrum, and spectrogram * -- A play thread which * ---- just repeats a note. * * PIO: There are three PIO state machines that generate the video. * See: https://vanhunteradams.com/Pico/VGA/VGA.html */ // ========================================== // === VGA graphics library // ========================================== #include "vga16_graphics.h" #include #include #include #include "pico/stdlib.h" #include "hardware/pio.h" #include "hardware/adc.h" #include "hardware/pwm.h" #include "hardware/irq.h" #include "hardware/spi.h" // ========================================== // === hardware and protothreads globals // ========================================== #include "hardware/sync.h" #include "hardware/timer.h" #include "pico/multicore.h" #include "string.h" // protothreads header #include "pt_cornell_rp2040_v1_3.h" float serial_value ; char serial_value_input[32] ; int play_scale = true ; // ========================================== // === fixed point s15x16 // ========================================== // s15x16 fixed point macros == // == resolution 2^-16 = 1.5e-5 // == dynamic range is 32767/-32768 typedef signed int s15x16; #define muls15x16(a,b) ((s15x16)(((( signed long long )(a))*(( signed long long )(b)))>>16)) //multiply two fixed 16:16 #define float_to_s15x16(a) ((s15x16)((a)*65536.0)) // 2^16 #define s15x16_to_float(a) ((float)(a)/65536.0) #define s15x16_to_int(a) ((int)((a)>>16)) #define int_to_s15x16(a) ((s15x16)((a)<<16)) #define divs15x16(a,b) ((s15x16)((((signed long long)(a)<<16)/(b)))) #define abss15x16(a) abs(a) // ========================================== // === fixed point s1x14 for FFT // ========================================== // s1.14 format -- short format is faster // == resolution 2^-14 = 6.1035e-5 // == dynamic range is +1.9999/-2.0 typedef signed short s1x14 ; #define muls1x14(a,b) ((s1x14)((((int)(a))*((int)(b)))>>14)) #define float_to_s1x14(a) ((s1x14)((a)*16384.0)) // 2^14 #define s1x14_to_float(a) ((float)(a)/16384.0) #define abss1x14(a) abs(a) #define divs1x14(a,b) ((s1x14)((((signed int)(a)<<14)/(b)))) // make the integer part of s5x16 (max +/- 2048) map to +/-1 in s1x14 #define s15x16_to_s1x14(a) ((s1x14)((((s15x16)(a)>>14)))) // string-specific multiply macros // for _Accum fixed point #define times0pt5(a) ((a)>>1) #define times0pt25(a) ((a)>>2) #define times2pt0(a) ((a)<<1) #define times4pt0(a) ((a)<<2) #define times0pt9998(a) ((a)-((a)>>12)) //>>10 #define times0pt999(a) ((a)-((a)>>10)) //>>10 #define times0pt9999(a) ((a)-((a)>>13)) #define times0pt99999(a) ((a)-((a)>>16)) // ========================================== // === set up SPI DAC // ========================================== // All SPI DAC setup was gotten from HUnter Adams // https://vanhunteradams.com/Pico/TimerIRQ/SPI_DDS.html // DAC parameters // A-channel, 1x, active #define DAC_config_chan_A 0b0011000000000000 // B-channel, 1x, active #define DAC_config_chan_B 0b1011000000000000 //SPI configurations #define PIN_CS 5 #define PIN_SCK 6 #define PIN_MOSI 7 #define SPI_PORT spi0 // data for the spi port uint16_t DAC_data ; // ========================================== // === set up DDS and timer ISR // ========================================== // 1/Fs in microseconds // 40 KSamples/sec volatile int alarm_period = 25 ; // inputs float Fs, Fout, Fmod ; // C3 D3 E3 F3 G3 A3 B3 C4 float notes[8]={130.8, 146.8, 164.8, 174.6, 196.0, 220.0, 246.9, 261.6}; // volatile int note_start = true ; // ========================================== // === set up timer ISR used in this pgm // ========================================== // === timer alarm ======================== // !! modifiying alarm zero trashes the cpu // and causes LED 4 long - 4 short // !! DO NOT USE alarm 0 // This low-level setup is ocnsiderably faster to execute // than the hogh-level callback #define ALARM_NUM 1 #define ALARM_IRQ TIMER_IRQ_1 // ISR interval will be 10 uSec // // the actual ISR void compute_sample(void); // static void alarm_irq(void) { // mark ISR entry gpio_put(2,1); // Clear the alarm irq hw_clear_bits(&timer_hw->intr, 1u << ALARM_NUM); // arm the next interrupt // Write the lower 32 bits of the target time to the alarm to arm it timer_hw->alarm[ALARM_NUM] = timer_hw->timerawl + alarm_period ; // // the routine which actually does the PDE compute_sample(); // mark ISR exit gpio_put(2,0); } // set up the timer alarm ISR static void alarm_in_us(uint32_t delay_us) { // Enable the interrupt for our alarm (the timer outputs 4 alarm irqs) hw_set_bits(&timer_hw->inte, 1u << ALARM_NUM); // Set irq handler for alarm irq irq_set_exclusive_handler(ALARM_IRQ, alarm_irq); // Enable the alarm irq irq_set_enabled(ALARM_IRQ, true); // Enable interrupt in block and at processor // Alarm is only 32 bits uint64_t target = timer_hw->timerawl + delay_us; // Write the lower 32 bits of the target time to the alarm which // will arm it timer_hw->alarm[ALARM_NUM] = (uint32_t) target; } // =========================================== // dSP definitions // =========================================== // // FFT setup #define N_WAVE 2048 //1024 #define LOG2_N_WAVE 11 //10 /* log2(N_WAVE) 0 */ s1x14 Sinewave[N_WAVE]; // a table of sines for the FFT s1x14 window[N_WAVE]; // a table of window values for the FFT s1x14 fr[N_WAVE], fi[N_WAVE]; // input data // dds output to FFT s1x14 dds[N_WAVE] ; // the dds output from ISR // index into dds buffer int buffer_index ; // displa points for graphiics short display_data[N_WAVE] ; short fft_display_data[N_WAVE] ; short log_display_data[N_WAVE] ; // ================================== // === Init FFT arrays //==================================== void FFTinit(void){ // one cycle sine table // required for FFT for (int ii = 0; ii < N_WAVE; ii++) { // one cycle per window for FFT -- scall amp for number of bits Sinewave[ii] = float_to_s1x14(0.5 * sin(6.283 * ((float) ii) / N_WAVE)); // Raised cos window // I think the spectrgraph looks better with flat window window[ii] = float_to_s1x14(1.0 ) ;//- cos(6.283 * ((float) ii) / (N_WAVE - 1))); } } // ================================== // === FFT //==================================== void FFTfix(s1x14 fr[], s1x14 fi[], int m){ //Adapted from code by: //Tom Roberts 11/8/89 and Malcolm Slaney 12/15/94 malcolm@interval.com //fr[n],fi[n] are real,imaginary arrays, INPUT AND RESULT. //size of data = 2**m // This routine does foward transform only int mr,nn,i,j,L,k,istep, n; s1x14 qr,qi,tr,ti,wr,wi; mr = 0; n = 1<>= 1; while(mr+L > nn); mr = (mr & (L-1)) + L; if(mr <= m) continue; tr = fr[m]; fr[m] = fr[mr]; fr[mr] = tr; ti = fi[m]; //for real inputs, don't need this fi[m] = fi[mr]; //for real inputs, don't need this fi[mr] = ti; //for real inputs, don't need this } L = 1; k = LOG2_N_WAVE-1; while(L < n) { istep = L << 1; for(m=0; m>= 1; //do need if scale table //wi >>= 1; for(i=m; i> 1; qi = fi[i] >> 1; fr[j] = qr - tr; fi[j] = qi - ti; fr[i] = qr + tr; fi[i] = qi + ti; } } --k; L = istep; } } //==================================== // === magnitude approx good to about +/-2% // see https://en.wikipedia.org/wiki/Alpha_max_plus_beta_min_algorithm #define min(a,b) (((a)<(b))?(a):(b)) #define max(a,b) (((a)>(b))?(a):(b)) //==================================== void magnitude(s1x14 fr[], s1x14 fi[], int length){ s1x14 mmax, mmin ; s1x14 c1 = float_to_s1x14(0.89820) ; s1x14 c2 = float_to_s1x14(0.48597) ; for (int ii = 0; ii < length; ii++) { mmin = min(abs(fr[ii]), abs(fi[ii])); //>>9 mmax = max(abs(fr[ii]), abs(fi[ii])); // reuse fr to hold magnitude fr[ii] = max(mmax, (muls1x14(mmax,c1) + muls1x14(mmin,c2) )); fi[ii] = 0; } } // ================================== // === approx log2 for plotting //==================================== #define log_min 0x00 // reuse fr to hold log magnitude // shifting finds most significant bit // then make approxlog = ly + (fr-y)./(y) + 0.043; // BUT for an 8-bit approx (4 bit ly and 4-bit fraction) // ly 1<=ly<=14 // omit the 0.043 because it is too small for 4-bit fraction void log2_approx(s1x14 fr[], int length) { // int sx, y, ly, temp ; for (int i = 0; i < length; i++) { // interpret bits as integer sx = fr[i]; y=1; ly=0; while(sx>1) { y=y*2; ly=ly+1; sx=sx>>1; } // shift ly into upper 4-bits as integer part of log // take bits below y and shift into lower 4-bits // !!NOTE that fr is no longer in s1x14 format!! fr[i] = ((ly)<<4) + ((fr[i]-y)>>(ly-4) ) ; // bound the noise at low amp if(fr[i]>1 ; new_string_temp = muls15x16(rho, (string_n[i-1] + string_n[i+1] - times2pt0(string_n[i]))) ; new_string[i] = times0pt9999(new_string_temp + times2pt0(string_n[i]) - times0pt9999(string_n_1[i])) ; } memcpy(string_n_1, string_n, copy_len); memcpy(string_n, new_string, copy_len); int temp = s15x16_to_int(string_n[output_pos]); DAC_data = (DAC_config_chan_A | (( temp + 2048) & 0xfff)) ; // Write data to DAC // spi_write16_blocking(SPI_PORT, &DAC_data, 1) ; // nonblocking SPI write spi0_hw->dr = DAC_data ; // move time ahead //note_time += onefix ; // save in buffer for FFT if(buffer_index < N_WAVE){ dds[buffer_index++] = (short)(temp<<2) ; } } // current amp > 0 } // end ISR call // ================================================== // === fft thread -- RUNNING on core 1 // ================================================== // static PT_THREAD (protothread_fft(struct pt *pt)) { PT_BEGIN(pt); static short time_column ; static short fr_disp ; // green > yellow > red static short color_map[10] ={0, 0, 0, 4, 5, 2, 9, 11, 11, 8}; //static short color_map[20] ={0, 0, 0, 0, 0, 0, 0, 4, 4, 5, 2, 9, 8, 8, 15}; static short thread_time ; PT_INTERVAL_INIT() ; FFTinit(); time_column = 110; while(1) { // //wait for synthesis ISR to fill the FFT buffer PT_YIELD_UNTIL(pt, buffer_index == N_WAVE) ; // and copy dds to real FFT input memcpy(fr, dds, N_WAVE*2) ; // start loading next buffer in ISR buffer_index = 0 ; // // for (int i=0; i>2), 0))] ; //4-1 drawPixel(time_column, 480-i, fr_disp ) ; drawPixel(time_column+1, 480-i, fr_disp ) ; } // NEVER exit while } // END WHILE(1) PT_END(pt); } // FFT thread // ======================================== // === core 1 main -- started in main below // ======================================== void core1_main(){ // fire off synthesis interrupt alarm_in_us(alarm_period); // === add threads ==================== // for core 1 //pt_add_thread(protothread_FM) ; //pt_add_thread(protothread_fft) ; pt_add_thread(protothread_play) ; // // === initalize the scheduler ========== pt_schedule_start ; // NEVER exits // ====================================== } // ======================================== // === core 0 main // ======================================== int main(){ // dds table for FM synth int i = 0 ; //while (i<256) { // sine table is in naural +1/-1 range // wave_table[i] = float_to_fix(sin(2*3.1416*i/256)) ; // i++ ; // } // start the serial i/o stdio_init_all() ; // announce the threader version on system reset printf("\n\rProtothreads RP2040 v1.3 two-core, priority\n\r"); // Initialize SPI channel (channel, baud rate set to 20MHz) // connected to spi DAC spi_init(SPI_PORT, 20000000) ; // Format (channel, data bits per transfer, polarity, phase, order) spi_set_format(SPI_PORT, 16, 0, 0, 0); // Map SPI signals to GPIO ports //gpio_set_function(PIN_MISO, GPIO_FUNC_SPI); gpio_set_function(PIN_SCK, GPIO_FUNC_SPI); gpio_set_function(PIN_MOSI, GPIO_FUNC_SPI); gpio_set_function(PIN_CS, GPIO_FUNC_SPI) ; // monitor ISR gpio_init(2) ; gpio_set_dir(2, GPIO_OUT) ; // Initialize the VGA screen initVGA() ; for (int i=1; i