dmx/firmware/main.c

   1 /*
   2  *      DMX512 Interface
   3  *
   4  *      (c) 2020 Martin Mareš <mj@ucw.cz>
   5  */
   6
   7 #include "util.h"
   8 #include "interface.h"
   9
  10 #include <libopencm3/cm3/cortex.h>
  11 #include <libopencm3/cm3/nvic.h>
  12 #include <libopencm3/cm3/systick.h>
  13 #include <libopencm3/cm3/scb.h>
  14 #include <libopencm3/stm32/rcc.h>
  15 #include <libopencm3/stm32/desig.h>
  16 #include <libopencm3/stm32/gpio.h>
  17 #include <libopencm3/stm32/timer.h>
  18 #include <libopencm3/stm32/usart.h>
  19 #include <libopencm3/usb/dfu.h>
  20 #include <libopencm3/usb/usbd.h>
  21
  22 #include <string.h>
  23
  24 /*** Hardware init ***/
  25
  26 static void clock_init(void)
  27 {
  28         rcc_clock_setup_in_hse_8mhz_out_72mhz();
  29
  30         rcc_periph_clock_enable(RCC_GPIOA);
  31         rcc_periph_clock_enable(RCC_GPIOB);
  32         rcc_periph_clock_enable(RCC_GPIOC);
  33         rcc_periph_clock_enable(RCC_TIM3);
  34         rcc_periph_clock_enable(RCC_USART1);
  35         rcc_periph_clock_enable(RCC_USART3);
  36         rcc_periph_clock_enable(RCC_USB);
  37
  38         rcc_periph_reset_pulse(RST_GPIOA);
  39         rcc_periph_reset_pulse(RST_GPIOB);
  40         rcc_periph_reset_pulse(RST_GPIOC);
  41         rcc_periph_reset_pulse(RST_TIM3);
  42         rcc_periph_reset_pulse(RST_USART1);
  43         rcc_periph_reset_pulse(RST_USART3);
  44         rcc_periph_reset_pulse(RST_USB);
  45 }
  46
  47 static void gpio_init(void)
  48 {
  49         // PA9 = TXD1 for debugging console
  50         // PA10 = RXD1 for debugging console
  51         gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO9);
  52         gpio_set_mode(GPIOA, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO10);
  53
  54         // PC13 = BluePill LED
  55         gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO13);
  56         gpio_clear(GPIOC, GPIO13);
  57
  58         // PB10 = TXD3 for DMX
  59         // PB11 = RXD3 for DMX
  60         gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, GPIO10);
  61         gpio_set_mode(GPIOB, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO11);
  62 }
  63
  64 static void usart_init(void)
  65 {
  66         usart_set_baudrate(USART1, 115200);
  67         usart_set_databits(USART1, 8);
  68         usart_set_stopbits(USART1, USART_STOPBITS_1);
  69         usart_set_mode(USART1, USART_MODE_TX);
  70         usart_set_parity(USART1, USART_PARITY_NONE);
  71         usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE);
  72
  73         usart_enable(USART1);
  74 }
  75
  76 /*** System ticks ***/
  77
  78 static volatile u32 ms_ticks;
  79
  80 void sys_tick_handler(void)
  81 {
  82         ms_ticks++;
  83 }
  84
  85 static void tick_init(void)
  86 {
  87         systick_set_frequency(1000, CPU_CLOCK_MHZ * 1000000);
  88         systick_counter_enable();
  89         systick_interrupt_enable();
  90 }
  91
  92 static void delay_ms(uint ms)
  93 {
  94         u32 start_ticks = ms_ticks;
  95         while (ms_ticks - start_ticks < ms)
  96                 ;
  97 }
  98
  99 /*** DMX ***/
 100
 101 #define DMX_MAX_PACKET_SIZE 64
 102
 103 static volatile byte dmx_state;
 104 static byte dmx_packet[DMX_MAX_PACKET_SIZE];
 105 static byte dmx_pos, dmx_len;
 106
 107 static byte dmx_next_packet[DMX_MAX_PACKET_SIZE];
 108 static byte dmx_next_len;
 109
 110 #undef DEBUG_DMX
 111 #ifdef DEBUG_DMX
 112 #define DMX_DEBUG(ch) debug_putc(ch)
 113 #else
 114 #define DMX_DEBUG(ch) do { } while (0)
 115 #endif
 116
 117 enum dmx_state {
 118         DMX_STATE_IDLE = 0,
 119         DMX_STATE_BREAK,
 120         DMX_STATE_MARK,
 121         DMX_STATE_DATA,
 122         DMX_STATE_LAST_BYTE,
 123         DMX_STATE_GAP,
 124 };
 125
 126 static void dmx_init(void)
 127 {
 128         usart_set_baudrate(USART3, 250000);
 129         usart_set_databits(USART3, 8);
 130         usart_set_stopbits(USART3, USART_STOPBITS_2);
 131         usart_set_mode(USART3, USART_MODE_TX);
 132         usart_set_parity(USART3, USART_PARITY_NONE);
 133         usart_set_flow_control(USART3, USART_FLOWCONTROL_NONE);
 134         nvic_enable_irq(NVIC_USART3_IRQ);
 135
 136         usart_enable(USART3);
 137
 138         timer_set_prescaler(TIM3, CPU_CLOCK_MHZ - 1);   // 1 MHz
 139         timer_set_mode(TIM3, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
 140         timer_update_on_overflow(TIM3);
 141         timer_disable_preload(TIM3);
 142         timer_one_shot_mode(TIM3);
 143         timer_enable_irq(TIM3, TIM_DIER_UIE);
 144         nvic_enable_irq(NVIC_TIM3_IRQ);
 145
 146         // Until we get data from USB, send "turn everything off" packets
 147         memset(dmx_next_packet, 0, DMX_MAX_PACKET_SIZE);
 148         dmx_next_len = DMX_MAX_PACKET_SIZE;
 149 }
 150
 151 void tim3_isr(void)
 152 {
 153         if (TIM_SR(TIM3) & TIM_SR_UIF) {
 154                 TIM_SR(TIM3) &= ~TIM_SR_UIF;
 155                 switch (dmx_state) {
 156                         case DMX_STATE_BREAK:
 157                                 // Send mark for 50 μs
 158                                 DMX_DEBUG('m');
 159                                 dmx_state = DMX_STATE_MARK;
 160                                 gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, GPIO10);
 161                                 timer_set_period(TIM3, 199);
 162                                 timer_generate_event(TIM3, TIM_EGR_UG);
 163                                 timer_enable_counter(TIM3);
 164                                 break;
 165                         case DMX_STATE_MARK:
 166                                 // Start sending data bytes
 167                                 DMX_DEBUG('d');
 168                                 dmx_state = DMX_STATE_DATA;
 169                                 usart_enable_tx_interrupt(USART3);
 170                                 break;
 171                         case DMX_STATE_GAP:
 172                                 DMX_DEBUG('>');
 173                                 dmx_state = DMX_STATE_IDLE;
 174                                 break;
 175                 }
 176         }
 177 }
 178
 179 void usart3_isr(void)
 180 {
 181         u32 status = USART_SR(USART3);
 182
 183         if (dmx_state == DMX_STATE_DATA) {
 184                 if (status & USART_SR_TXE) {
 185                         if (dmx_pos < dmx_len) {
 186                                 DMX_DEBUG('.');
 187                                 usart_send(USART3, dmx_packet[dmx_pos++]);
 188                         } else {
 189                                 // The transmitter is double-buffered, so at this moment, it is transmitting
 190                                 // the last byte of the frame. Wait until transfer is completed.
 191                                 DMX_DEBUG('l');
 192                                 usart_disable_tx_interrupt(USART3);
 193                                 USART_CR1(USART3) |= USART_CR1_TCIE;
 194                                 dmx_state = DMX_STATE_LAST_BYTE;
 195                         }
 196                 }
 197         } else if (dmx_state == DMX_STATE_LAST_BYTE) {
 198                 // Transfer of the last byte is complete, but we have to wait
 199                 // before the start of the next packet: minimum time between two
 200                 // breaks must be at least 1204 μs. We already sent a 200μs break,
 201                 // 200μs mark, and dmx_len 44μs data slots.
 202                 USART_CR1(USART3) &= ~USART_CR1_TCIE;
 203                 uint sent = 200 + 200 + 44*dmx_len;
 204                 if (sent < 1300) {
 205                         DMX_DEBUG('g');
 206                         dmx_state = DMX_STATE_GAP;
 207                         timer_set_period(TIM3, 1300 - sent - 1);
 208                         timer_generate_event(TIM3, TIM_EGR_UG);
 209                         timer_enable_counter(TIM3);
 210                 } else {
 211                         DMX_DEBUG('>');
 212                         dmx_state = DMX_STATE_IDLE;
 213                 }
 214         }
 215 }
 216
 217 static void dmx_send(void)
 218 {
 219         if (dmx_state != DMX_STATE_IDLE)
 220                 return;
 221
 222         if (!dmx_len)
 223                 return;
 224
 225         dmx_pos = 0;
 226
 227         // Send break for 200 μs
 228         DMX_DEBUG('<');
 229         dmx_state = DMX_STATE_BREAK;
 230         gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, GPIO10);
 231         gpio_clear(GPIOB, GPIO10);
 232
 233         timer_set_period(TIM3, 199);
 234         timer_generate_event(TIM3, TIM_EGR_UG);
 235         timer_enable_counter(TIM3);
 236 }
 237
 238 /*** USB ***/
 239
 240 static usbd_device *usbd_dev;
 241
 242 enum usb_string {
 243         STR_MANUFACTURER = 1,
 244         STR_PRODUCT,
 245         STR_SERIAL,
 246 };
 247
 248 static char usb_serial_number[13];
 249
 250 static const char *usb_strings[] = {
 251         "United Computer Wizards",
 252         "DMX512 Interface",
 253         usb_serial_number,
 254 };
 255
 256 static const struct usb_device_descriptor device = {
 257         .bLength = USB_DT_DEVICE_SIZE,
 258         .bDescriptorType = USB_DT_DEVICE,
 259         .bcdUSB = 0x0200,
 260         .bDeviceClass = 0xFF,
 261         .bDeviceSubClass = 0,
 262         .bDeviceProtocol = 0,
 263         .bMaxPacketSize0 = 64,
 264         .idVendor = DMX_USB_VENDOR,
 265         .idProduct = DMX_USB_PRODUCT,
 266         .bcdDevice = DMX_USB_VERSION,
 267         .iManufacturer = STR_MANUFACTURER,
 268         .iProduct = STR_PRODUCT,
 269         .iSerialNumber = STR_SERIAL,
 270         .bNumConfigurations = 1,
 271 };
 272
 273 static const struct usb_endpoint_descriptor endpoints[] = {{
 274         // Bulk end-point for sending values to DMX
 275         .bLength = USB_DT_ENDPOINT_SIZE,
 276         .bDescriptorType = USB_DT_ENDPOINT,
 277         .bEndpointAddress = 0x01,
 278         .bmAttributes = USB_ENDPOINT_ATTR_BULK,
 279         .wMaxPacketSize = 64,
 280         .bInterval = 1,
 281 }};
 282
 283 static const struct usb_interface_descriptor iface = {
 284         .bLength = USB_DT_INTERFACE_SIZE,
 285         .bDescriptorType = USB_DT_INTERFACE,
 286         .bInterfaceNumber = 0,
 287         .bAlternateSetting = 0,
 288         .bNumEndpoints = 1,
 289         .bInterfaceClass = 0xFF,
 290         .bInterfaceSubClass = 0,
 291         .bInterfaceProtocol = 0,
 292         .iInterface = 0,
 293         .endpoint = endpoints,
 294 };
 295
 296 static const struct usb_dfu_descriptor dfu_function = {
 297         .bLength = sizeof(struct usb_dfu_descriptor),
 298         .bDescriptorType = DFU_FUNCTIONAL,
 299         .bmAttributes = USB_DFU_CAN_DOWNLOAD | USB_DFU_WILL_DETACH,
 300         .wDetachTimeout = 255,
 301         .wTransferSize = 1024,
 302         .bcdDFUVersion = 0x0100,
 303 };
 304
 305 static const struct usb_interface_descriptor dfu_iface = {
 306         .bLength = USB_DT_INTERFACE_SIZE,
 307         .bDescriptorType = USB_DT_INTERFACE,
 308         .bInterfaceNumber = 1,
 309         .bAlternateSetting = 0,
 310         .bNumEndpoints = 0,
 311         .bInterfaceClass = 0xFE,
 312         .bInterfaceSubClass = 1,
 313         .bInterfaceProtocol = 1,
 314         .iInterface = 0,
 315
 316         .extra = &dfu_function,
 317         .extralen = sizeof(dfu_function),
 318 };
 319
 320 static const struct usb_interface ifaces[] = {{
 321         .num_altsetting = 1,
 322         .altsetting = &iface,
 323 }, {
 324         .num_altsetting = 1,
 325         .altsetting = &dfu_iface,
 326 }};
 327
 328 static const struct usb_config_descriptor config = {
 329         .bLength = USB_DT_CONFIGURATION_SIZE,
 330         .bDescriptorType = USB_DT_CONFIGURATION,
 331         .wTotalLength = 0,
 332         .bNumInterfaces = 2,
 333         .bConfigurationValue = 1,
 334         .iConfiguration = 0,
 335         .bmAttributes = 0x80,
 336         .bMaxPower = 50,        // multiplied by 2 mA
 337         .interface = ifaces,
 338 };
 339
 340 static byte usb_configured;
 341 static uint8_t usbd_control_buffer[64];
 342
 343 static void dfu_detach_complete(usbd_device *dev UNUSED, struct usb_setup_data *req UNUSED)
 344 {
 345         // Reset to bootloader, which implements the rest of DFU
 346         debug_printf("Switching to DFU\n");
 347         debug_flush();
 348         scb_reset_core();
 349 }
 350
 351 static enum usbd_request_return_codes dfu_control_cb(usbd_device *dev UNUSED,
 352         struct usb_setup_data *req,
 353         uint8_t **buf UNUSED,
 354         uint16_t *len UNUSED,
 355         void (**complete)(usbd_device *dev, struct usb_setup_data *req))
 356 {
 357         if (req->bmRequestType != 0x21 || req->bRequest != DFU_DETACH)
 358                 return USBD_REQ_NOTSUPP;
 359
 360         *complete = dfu_detach_complete;
 361         return USBD_REQ_HANDLED;
 362 }
 363
 364 static void ep01_cb(usbd_device *dev, uint8_t ep UNUSED)
 365 {
 366         // We received a frame from the USB host
 367         uint len = usbd_ep_read_packet(dev, 0x01, dmx_next_packet, DMX_MAX_PACKET_SIZE);
 368         debug_printf("USB: Host sent %u bytes\n", len);
 369         dmx_next_len = len;
 370 }
 371
 372 static void set_config_cb(usbd_device *dev, uint16_t wValue UNUSED)
 373 {
 374         usbd_register_control_callback(
 375                 dev,
 376                 USB_REQ_TYPE_CLASS | USB_REQ_TYPE_INTERFACE,
 377                 USB_REQ_TYPE_TYPE | USB_REQ_TYPE_RECIPIENT,
 378                 dfu_control_cb);
 379         usbd_ep_setup(dev, 0x01, USB_ENDPOINT_ATTR_BULK, 64, ep01_cb);
 380         usb_configured = 1;
 381 }
 382
 383 static void reset_cb(void)
 384 {
 385         debug_printf("USB: Reset\n");
 386         usb_configured = 0;
 387 }
 388
 389 static volatile bool usb_event_pending;
 390
 391 void usb_lp_can_rx0_isr(void)
 392 {
 393         /*
 394          *  We handle USB in the main loop to avoid race conditions between
 395          *  USB interrupts and other code. However, we need an interrupt to
 396          *  up the main loop from sleep.
 397          *
 398          *  We set up only the low-priority ISR, because high-priority ISR handles
 399          *  only double-buffered bulk transfers and isochronous transfers.
 400          */
 401         nvic_disable_irq(NVIC_USB_LP_CAN_RX0_IRQ);
 402         usb_event_pending = 1;
 403 }
 404
 405 static void usb_init(void)
 406 {
 407         // Simulate USB disconnect
 408         gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, GPIO11 | GPIO12);
 409         gpio_clear(GPIOA, GPIO11 | GPIO12);
 410         delay_ms(100);
 411
 412         usbd_dev = usbd_init(
 413                 &st_usbfs_v1_usb_driver,
 414                 &device,
 415                 &config,
 416                 usb_strings,
 417                 ARRAY_SIZE(usb_strings),
 418                 usbd_control_buffer,
 419                 sizeof(usbd_control_buffer)
 420         );
 421         usbd_register_reset_callback(usbd_dev, reset_cb);
 422         usbd_register_set_config_callback(usbd_dev, set_config_cb);
 423         usb_event_pending = 1;
 424 }
 425
 426 /*** Main ***/
 427
 428 int main(void)
 429 {
 430         clock_init();
 431         gpio_init();
 432         tick_init();
 433         usart_init();
 434         desig_get_unique_id_as_dfu(usb_serial_number);
 435
 436         debug_printf("Hail, Lord Damian! Thy DMX interface is ready.\n");
 437
 438         usb_init();
 439         dmx_init();
 440
 441         u32 last_blink = 0;
 442         u32 last_send = 0;
 443
 444         for (;;) {
 445                 if (ms_ticks - last_blink >= 100) {
 446                         debug_led_toggle();
 447                         last_blink = ms_ticks;
 448                         dmx_send();
 449                 }
 450
 451                 if (usb_event_pending) {
 452                         usbd_poll(usbd_dev);
 453                         usb_event_pending = 0;
 454                         nvic_clear_pending_irq(NVIC_USB_LP_CAN_RX0_IRQ);
 455                         nvic_enable_irq(NVIC_USB_LP_CAN_RX0_IRQ);
 456                 }
 457
 458                 if (dmx_state == DMX_STATE_IDLE) {
 459                         if (dmx_next_len) {
 460                                 // We have a new packet to send
 461                                 debug_printf("Sending new packet: %d bytes\n", dmx_next_len);
 462                                 memcpy(dmx_packet, dmx_next_packet, dmx_next_len);
 463                                 dmx_len = dmx_next_len;
 464                                 dmx_next_len = 0;
 465                                 dmx_send();
 466                                 last_send = ms_ticks;
 467                         } else if (ms_ticks - last_send >= 100) {
 468                                 // Re-send every 100 ms
 469                                 // debug_printf("Re-send: %d bytes\n", dmx_len);
 470                                 dmx_send();
 471                                 last_send = ms_ticks;
 472                         }
 473                 }
 474
 475                 wait_for_interrupt();
 476         }
 477
 478         return 0;
 479 }