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 static volatile byte dmx_state;
 102 static byte dmx_packet[64];
 103 static byte dmx_pos, dmx_len;
 104
 105 #define DEBUG_DMX
 106 #ifdef DEBUG_DMX
 107 #define DMX_DEBUG(ch) debug_putc(ch)
 108 #else
 109 #define DMX_DEBUG(ch) do { } while (0)
 110 #endif
 111
 112 enum dmx_state {
 113         DMX_STATE_IDLE = 0,
 114         DMX_STATE_BREAK,
 115         DMX_STATE_MARK,
 116         DMX_STATE_DATA,
 117         DMX_STATE_LAST_BYTE,
 118         DMX_STATE_GAP,
 119 };
 120
 121 static void dmx_init(void)
 122 {
 123         usart_set_baudrate(USART3, 250000);
 124         usart_set_databits(USART3, 8);
 125         usart_set_stopbits(USART3, USART_STOPBITS_1);
 126         usart_set_mode(USART3, USART_MODE_TX);
 127         usart_set_parity(USART3, USART_PARITY_NONE);
 128         usart_set_flow_control(USART3, USART_FLOWCONTROL_NONE);
 129         nvic_enable_irq(NVIC_USART3_IRQ);
 130
 131         usart_enable(USART3);
 132
 133         timer_set_prescaler(TIM3, CPU_CLOCK_MHZ - 1);   // 1 MHz
 134         timer_set_mode(TIM3, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
 135         timer_update_on_overflow(TIM3);
 136         timer_disable_preload(TIM3);
 137         timer_one_shot_mode(TIM3);
 138         timer_enable_irq(TIM3, TIM_DIER_UIE);
 139         nvic_enable_irq(NVIC_TIM3_IRQ);
 140 }
 141
 142 void tim3_isr(void)
 143 {
 144         if (TIM_SR(TIM3) & TIM_SR_UIF) {
 145                 TIM_SR(TIM3) &= ~TIM_SR_UIF;
 146                 switch (dmx_state) {
 147                         case DMX_STATE_BREAK:
 148                                 // Send mark for 50 μs
 149                                 DMX_DEBUG('m');
 150                                 dmx_state = DMX_STATE_MARK;
 151                                 gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, GPIO10);
 152                                 timer_set_period(TIM3, 199);
 153                                 timer_generate_event(TIM3, TIM_EGR_UG);
 154                                 timer_enable_counter(TIM3);
 155                                 break;
 156                         case DMX_STATE_MARK:
 157                                 // Start sending data bytes
 158                                 DMX_DEBUG('d');
 159                                 dmx_state = DMX_STATE_DATA;
 160                                 usart_enable_tx_interrupt(USART3);
 161                                 break;
 162                         case DMX_STATE_GAP:
 163                                 DMX_DEBUG('>');
 164                                 dmx_state = DMX_STATE_IDLE;
 165                                 break;
 166                 }
 167         }
 168 }
 169
 170 void usart3_isr(void)
 171 {
 172         u32 status = USART_SR(USART3);
 173
 174         if (dmx_state == DMX_STATE_DATA) {
 175                 if (status & USART_SR_TXE) {
 176                         if (dmx_pos < dmx_len) {
 177                                 DMX_DEBUG('.');
 178                                 usart_send(USART3, dmx_packet[dmx_pos++]);
 179                         } else {
 180                                 // The transmitter is double-buffered, so at this moment, it is transmitting
 181                                 // the last byte of the frame. Wait until transfer is completed.
 182                                 DMX_DEBUG('l');
 183                                 usart_disable_tx_interrupt(USART3);
 184                                 USART_CR1(USART3) |= USART_CR1_TCIE;
 185                                 dmx_state = DMX_STATE_LAST_BYTE;
 186                         }
 187                 }
 188         } else if (dmx_state == DMX_STATE_LAST_BYTE) {
 189                 // Transfer of the last byte is complete, but we have to wait
 190                 // before the start of the next packet: minimum time between two
 191                 // breaks must be at least 1204 μs. We already sent a 200μs break,
 192                 // 200μs mark, and dmx_len 40μs data slots.
 193                 USART_CR1(USART3) &= ~USART_CR1_TCIE;
 194                 uint sent = 200 + 200 + 40*dmx_len;
 195                 if (sent < 1300) {
 196                         DMX_DEBUG('g');
 197                         dmx_state = DMX_STATE_GAP;
 198                         timer_set_period(TIM3, 1300 - sent - 1);
 199                         timer_generate_event(TIM3, TIM_EGR_UG);
 200                         timer_enable_counter(TIM3);
 201                 } else {
 202                         DMX_DEBUG('>');
 203                         dmx_state = DMX_STATE_IDLE;
 204                 }
 205         }
 206 }
 207
 208 static void dmx_send(void)
 209 {
 210         if (dmx_state != DMX_STATE_IDLE)
 211                 return;
 212
 213         dmx_packet[0] = 0;
 214         dmx_packet[1] = 0xff;   // warm
 215         dmx_packet[2] = 0xff;   // cold
 216         dmx_packet[3] = 0;
 217         dmx_packet[4] = 0;
 218         dmx_pos = 0;
 219         dmx_len = 5;
 220
 221         // Send break for 200 μs
 222         DMX_DEBUG('<');
 223         dmx_state = DMX_STATE_BREAK;
 224         gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, GPIO10);
 225         gpio_clear(GPIOB, GPIO10);
 226
 227         timer_set_period(TIM3, 199);
 228         timer_generate_event(TIM3, TIM_EGR_UG);
 229         timer_enable_counter(TIM3);
 230 }
 231
 232 /*** USB ***/
 233
 234 static usbd_device *usbd_dev;
 235
 236 enum usb_string {
 237         STR_MANUFACTURER = 1,
 238         STR_PRODUCT,
 239         STR_SERIAL,
 240 };
 241
 242 static char usb_serial_number[13];
 243
 244 static const char *usb_strings[] = {
 245         "United Computer Wizards",
 246         "DMX512 Interface",
 247         usb_serial_number,
 248 };
 249
 250 static const struct usb_device_descriptor device = {
 251         .bLength = USB_DT_DEVICE_SIZE,
 252         .bDescriptorType = USB_DT_DEVICE,
 253         .bcdUSB = 0x0200,
 254         .bDeviceClass = 0xFF,
 255         .bDeviceSubClass = 0,
 256         .bDeviceProtocol = 0,
 257         .bMaxPacketSize0 = 64,
 258         .idVendor = DMX_USB_VENDOR,
 259         .idProduct = DMX_USB_PRODUCT,
 260         .bcdDevice = DMX_USB_VERSION,
 261         .iManufacturer = STR_MANUFACTURER,
 262         .iProduct = STR_PRODUCT,
 263         .iSerialNumber = STR_SERIAL,
 264         .bNumConfigurations = 1,
 265 };
 266
 267 static const struct usb_endpoint_descriptor endpoints[] = {{
 268         // Bulk end-point for sending values to DMX
 269         .bLength = USB_DT_ENDPOINT_SIZE,
 270         .bDescriptorType = USB_DT_ENDPOINT,
 271         .bEndpointAddress = 0x01,
 272         .bmAttributes = USB_ENDPOINT_ATTR_BULK,
 273         .wMaxPacketSize = 64,
 274         .bInterval = 1,
 275 }};
 276
 277 static const struct usb_interface_descriptor iface = {
 278         .bLength = USB_DT_INTERFACE_SIZE,
 279         .bDescriptorType = USB_DT_INTERFACE,
 280         .bInterfaceNumber = 0,
 281         .bAlternateSetting = 0,
 282         .bNumEndpoints = 1,
 283         .bInterfaceClass = 0xFF,
 284         .bInterfaceSubClass = 0,
 285         .bInterfaceProtocol = 0,
 286         .iInterface = 0,
 287         .endpoint = endpoints,
 288 };
 289
 290 static const struct usb_dfu_descriptor dfu_function = {
 291         .bLength = sizeof(struct usb_dfu_descriptor),
 292         .bDescriptorType = DFU_FUNCTIONAL,
 293         .bmAttributes = USB_DFU_CAN_DOWNLOAD | USB_DFU_WILL_DETACH,
 294         .wDetachTimeout = 255,
 295         .wTransferSize = 1024,
 296         .bcdDFUVersion = 0x0100,
 297 };
 298
 299 static const struct usb_interface_descriptor dfu_iface = {
 300         .bLength = USB_DT_INTERFACE_SIZE,
 301         .bDescriptorType = USB_DT_INTERFACE,
 302         .bInterfaceNumber = 1,
 303         .bAlternateSetting = 0,
 304         .bNumEndpoints = 0,
 305         .bInterfaceClass = 0xFE,
 306         .bInterfaceSubClass = 1,
 307         .bInterfaceProtocol = 1,
 308         .iInterface = 0,
 309
 310         .extra = &dfu_function,
 311         .extralen = sizeof(dfu_function),
 312 };
 313
 314 static const struct usb_interface ifaces[] = {{
 315         .num_altsetting = 1,
 316         .altsetting = &iface,
 317 }, {
 318         .num_altsetting = 1,
 319         .altsetting = &dfu_iface,
 320 }};
 321
 322 static const struct usb_config_descriptor config = {
 323         .bLength = USB_DT_CONFIGURATION_SIZE,
 324         .bDescriptorType = USB_DT_CONFIGURATION,
 325         .wTotalLength = 0,
 326         .bNumInterfaces = 2,
 327         .bConfigurationValue = 1,
 328         .iConfiguration = 0,
 329         .bmAttributes = 0x80,
 330         .bMaxPower = 50,        // multiplied by 2 mA
 331         .interface = ifaces,
 332 };
 333
 334 static byte usb_configured;
 335 static uint8_t usbd_control_buffer[64];
 336
 337 static void dfu_detach_complete(usbd_device *dev UNUSED, struct usb_setup_data *req UNUSED)
 338 {
 339         // Reset to bootloader, which implements the rest of DFU
 340         debug_printf("Switching to DFU\n");
 341         debug_flush();
 342         scb_reset_core();
 343 }
 344
 345 static enum usbd_request_return_codes dfu_control_cb(usbd_device *dev UNUSED,
 346         struct usb_setup_data *req,
 347         uint8_t **buf UNUSED,
 348         uint16_t *len UNUSED,
 349         void (**complete)(usbd_device *dev, struct usb_setup_data *req))
 350 {
 351         if (req->bmRequestType != 0x21 || req->bRequest != DFU_DETACH)
 352                 return USBD_REQ_NOTSUPP;
 353
 354         *complete = dfu_detach_complete;
 355         return USBD_REQ_HANDLED;
 356 }
 357
 358 static void ep01_cb(usbd_device *dev, uint8_t ep UNUSED)
 359 {
 360         // We received a frame from the USB host
 361         byte buf[64];
 362         uint len = usbd_ep_read_packet(dev, 0x01, buf, sizeof(buf));
 363         debug_printf("USB: Host sent %u bytes\n", len);
 364 }
 365
 366 static void set_config_cb(usbd_device *dev, uint16_t wValue UNUSED)
 367 {
 368         usbd_register_control_callback(
 369                 dev,
 370                 USB_REQ_TYPE_CLASS | USB_REQ_TYPE_INTERFACE,
 371                 USB_REQ_TYPE_TYPE | USB_REQ_TYPE_RECIPIENT,
 372                 dfu_control_cb);
 373         usbd_ep_setup(dev, 0x01, USB_ENDPOINT_ATTR_BULK, 64, ep01_cb);
 374         usb_configured = 1;
 375 }
 376
 377 static void reset_cb(void)
 378 {
 379         debug_printf("USB: Reset\n");
 380         usb_configured = 0;
 381 }
 382
 383 static volatile bool usb_event_pending;
 384
 385 void usb_lp_can_rx0_isr(void)
 386 {
 387         /*
 388          *  We handle USB in the main loop to avoid race conditions between
 389          *  USB interrupts and other code. However, we need an interrupt to
 390          *  up the main loop from sleep.
 391          *
 392          *  We set up only the low-priority ISR, because high-priority ISR handles
 393          *  only double-buffered bulk transfers and isochronous transfers.
 394          */
 395         nvic_disable_irq(NVIC_USB_LP_CAN_RX0_IRQ);
 396         usb_event_pending = 1;
 397 }
 398
 399 static void usb_init(void)
 400 {
 401         // Simulate USB disconnect
 402         gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, GPIO11 | GPIO12);
 403         gpio_clear(GPIOA, GPIO11 | GPIO12);
 404         delay_ms(100);
 405
 406         usbd_dev = usbd_init(
 407                 &st_usbfs_v1_usb_driver,
 408                 &device,
 409                 &config,
 410                 usb_strings,
 411                 ARRAY_SIZE(usb_strings),
 412                 usbd_control_buffer,
 413                 sizeof(usbd_control_buffer)
 414         );
 415         usbd_register_reset_callback(usbd_dev, reset_cb);
 416         usbd_register_set_config_callback(usbd_dev, set_config_cb);
 417         usb_event_pending = 1;
 418 }
 419
 420 /*** Main ***/
 421
 422 int main(void)
 423 {
 424         clock_init();
 425         gpio_init();
 426         tick_init();
 427         usart_init();
 428         desig_get_unique_id_as_dfu(usb_serial_number);
 429
 430         debug_printf("Hail, Lord Damian! Thy DMX interface is ready.\n");
 431
 432         usb_init();
 433         dmx_init();
 434
 435         u32 last_blink = 0;
 436
 437         for (;;) {
 438                 if (ms_ticks - last_blink >= 100) {
 439                         debug_led_toggle();
 440                         last_blink = ms_ticks;
 441                         dmx_send();
 442                 }
 443
 444                 if (usb_event_pending) {
 445                         usbd_poll(usbd_dev);
 446                         usb_event_pending = 0;
 447                         nvic_clear_pending_irq(NVIC_USB_LP_CAN_RX0_IRQ);
 448                         nvic_enable_irq(NVIC_USB_LP_CAN_RX0_IRQ);
 449                 }
 450
 451                 wait_for_interrupt();
 452         }
 453
 454         return 0;
 455 }