]> mj.ucw.cz Git - home-hw.git/blobdiff - bsb/firmware/main.c
BSB: Cleanup
[home-hw.git] / bsb / firmware / main.c
index e7237e1cf5101cc6f7fdb8b269a34fa5c2773e8e..bb0c48e53bf140ae98ade0e46e9da73180760dbf 100644 (file)
@@ -5,6 +5,7 @@
  */
 
 #include "util.h"
+#include "interface.h"
 
 #include <libopencm3/cm3/cortex.h>
 #include <libopencm3/cm3/nvic.h>
@@ -30,12 +31,14 @@ static void clock_init(void)
        rcc_periph_clock_enable(RCC_GPIOB);
        rcc_periph_clock_enable(RCC_GPIOC);
        rcc_periph_clock_enable(RCC_USART1);
+       rcc_periph_clock_enable(RCC_USART3);
        rcc_periph_clock_enable(RCC_USB);
 
        rcc_periph_reset_pulse(RST_GPIOA);
        rcc_periph_reset_pulse(RST_GPIOB);
        rcc_periph_reset_pulse(RST_GPIOC);
        rcc_periph_reset_pulse(RST_USART1);
+       rcc_periph_reset_pulse(RST_USART3);
        rcc_periph_reset_pulse(RST_USB);
 }
 
@@ -56,8 +59,7 @@ static void gpio_init(void)
 
        // PB10 = TXD3 for BSB
        // PB11 = RXD3 for BSB
-       // FIXME: TX turned off temporarily
-       // gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, GPIO10);
+       gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, GPIO10);
        gpio_set_mode(GPIOB, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO11);
 }
 
@@ -66,7 +68,7 @@ static void usart_init(void)
        usart_set_baudrate(USART1, 115200);
        usart_set_databits(USART1, 8);
        usart_set_stopbits(USART1, USART_STOPBITS_1);
-       usart_set_mode(USART1, USART_MODE_TX_RX);
+       usart_set_mode(USART1, USART_MODE_TX);
        usart_set_parity(USART1, USART_PARITY_NONE);
        usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE);
 
@@ -84,7 +86,7 @@ void sys_tick_handler(void)
 
 static void tick_init(void)
 {
-       systick_set_frequency(1000, 72000000);
+       systick_set_frequency(1000, CPU_CLOCK_MHZ * 1000000);
        systick_counter_enable();
        systick_interrupt_enable();
 }
@@ -96,69 +98,359 @@ static void delay_ms(uint ms)
                ;
 }
 
+/*** Random generator ***/
+
+static u32 rng_state;
+
+static u32 random_u32(void)
+{
+       rng_state *= 2654289733;
+       return rng_state;
+}
+
+static void random_init(void)
+{
+       u32 desig[3];
+       desig_get_unique_id(desig);
+       rng_state = desig[0] ^ desig[1] ^ desig[2];
+}
+
 /*** BSB ***/
 
 #define BSB_MAX_SIZE 32
-#define BSB_RX_TIMEOUT 2  // 1-2 ms => 2-4 byte periods of silence
+#define BSB_RX_TIMEOUT 10      // If no byte was received for this time, end the current frame [ms]
+#define BSB_TX_IDLE_LINE 100   // Consider the line idle if no byte was received for this time [ms]
+#define BSB_TX_MAX_ATTEMPTS 3
+#define BSB_TX_WAIT_LOG 8      // base 2 log of pre-frame waiting time in ms
+#define BSB_TX_TIMEOUT 10000   // Total time to transmit a frame including all retries and waiting for reply [ms]
+#define BSB_REPLY_TIMEOUT 1000 // How long to wait for a reply [ms]
+
+#undef DEBUG_BSB
+#ifdef DEBUG_BSB
+#define BSB_DEBUG(x) debug_putc(x)
+#else
+#define BSB_DEBUG(x) do { } while (0)
+#endif
+
+struct bsb_state {
+       byte rx_len;                    // Bytes received so far
+       byte rx_led;                    // Countdown to turning RX LED off
+       u16 rx_crc;
+       volatile u32 rx_timestamp;      // Last byte received
+
+       byte tx_state;                  // TX_STATE_xxx
+       byte tx_len;
+       byte tx_send_index;
+       byte tx_check_index;
+       byte tx_attempts;
+       byte tx_result;                 // TX_RESULT_xxx
+       u32 tx_start_timestamp;
+       u32 tx_ticks_to_send;
+       u32 tx_end_timestamp;
+       u32 reply_type_mask;            // Expected reply types (0=no reply)
+
+       byte rx_buf[BSB_MAX_SIZE];
+       byte tx_buf[BSB_MAX_SIZE];
+};
 
-static byte bsb_rx_buf[BSB_MAX_SIZE];
-static byte bsb_rx_len;
-static volatile u32 bsb_rx_timestamp;
+static struct bsb_state bsb;
 
-// Passing received frames to the main loop
-static byte bsb_rx_frame[BSB_MAX_SIZE];
+// Passing received frames and status codes to the main loop
+static byte bsb_rx_status_and_frame[1 + BSB_MAX_SIZE];
 static volatile byte bsb_rx_frame_len;
-static byte bsb_rx_frame_led;
-
-struct bsb_stat {
-       u32 rx_noise;
-       u32 rx_errors;
-       u32 rx_invalid;
-       u32 rx_overruns;
-       u32 rx_timeouts;
+static byte bsb_tx_result;
+
+enum bsb_tx_state {
+       TX_STATE_OFF,
+       TX_STATE_WAITING_FOR_IDLE_LINE,
+       TX_STATE_PRE_PACKET_DELAY,
+       TX_STATE_SENDING,
+       TX_STATE_SENT,
+       TX_STATE_WAITING_FOR_REPLY,
+       TX_STATE_COLLISION,
 };
 
-static struct bsb_stat bsb_stat;
+static struct bsb_stats bsb_stats;
+
+static void bsb_attempt_tx(void);
+
+static u16 bsb_crc_update(u16 crc, byte data)
+{
+       crc = crc ^ (data << 8);
+       for (uint i=0; i<8; i++) {
+               if (crc & 0x8000)
+                       crc = (crc << 1) ^ 0x1021;
+               else
+                       crc <<= 1;
+       }
+       return crc;
+}
 
 void usart3_isr(void)
 {
        u32 status = USART_SR(USART3);
 
        if (status & USART_SR_RXNE) {
-               uint ch = usart_recv(USART3);
-               bsb_rx_timestamp = ms_ticks;
-
-               if (status & (USART_SR_FE | USART_SR_ORE | USART_SR_NE)) {
-                       bsb_stat.rx_errors++;
-                       bsb_rx_len = 0;
-               } else if (!bsb_rx_len && ch != 0xdc) {
-                       // Waiting for start of frame
-                       bsb_stat.rx_noise++;
-               } else {
-                       bsb_rx_buf[bsb_rx_len++] = ch;
-                       if (bsb_rx_len < 4) {
-                               // First three bytes: SOF, source addr, destination addr
-                       } else if (bsb_rx_len == 4) {
-                               // Received length byte
-                               if (bsb_rx_buf[3] < 7 || bsb_rx_buf[3] > BSB_MAX_SIZE) {
-                                       bsb_stat.rx_invalid++;
-                                       bsb_rx_len = 0;
+               uint ch = ~usart_recv(USART3) & 0xff;
+               bsb.rx_timestamp = ms_ticks;
+#ifdef DEBUG_BSB
+               debug_printf(" %02x", ch);
+#endif
+
+               if (bsb.tx_state == TX_STATE_SENDING) {
+                       // We are hearing the echo of a transmitted packet, check it for collisions
+                       if (status & (USART_SR_FE | USART_SR_ORE | USART_SR_NE)) {
+                               BSB_DEBUG('e');
+                               bsb.tx_state = TX_STATE_COLLISION;
+                       } else if (ch == bsb.tx_buf[bsb.tx_check_index++]) {
+                               if (bsb.tx_check_index >= bsb.tx_len) {
+                                       BSB_DEBUG('d');
+                                       bsb.tx_state = TX_STATE_SENT;
                                }
-                       } else if (bsb_rx_len == bsb_rx_buf[3]) {
-                               // Received a complete frame: pass it to the main loop
-                               if (bsb_rx_frame_len) {
-                                       // The previous one was not sent yet
-                                       bsb_stat.rx_overruns++;
+                       } else {
+                               BSB_DEBUG('c');
+                               bsb.tx_state = TX_STATE_COLLISION;
+                       }
+               } else {
+                       // Regular receive
+                       if (status & (USART_SR_FE | USART_SR_ORE | USART_SR_NE)) {
+                               bsb_stats.rx_errors++;
+                               bsb.rx_len = 0;
+                       } else if (!bsb.rx_len) {
+                               // Start of frame
+                               if (ch == 0xdc) {
+                                       bsb.rx_buf[bsb.rx_len++] = ch;
+                                       bsb.rx_crc = bsb_crc_update(0, ch);
+                                       BSB_DEBUG('<');
                                } else {
-                                       memcpy(bsb_rx_frame, bsb_rx_buf, bsb_rx_buf[3]);
-                                       barrier();
-                                       bsb_rx_frame_len = bsb_rx_buf[3];
-                                       bsb_rx_frame_led = 100;
-                                       gpio_clear(GPIOB, GPIO1);
+                                       bsb_stats.rx_noise++;
+                                       BSB_DEBUG('?');
+                               }
+                       } else {
+                               bsb.rx_buf[bsb.rx_len++] = ch;
+                               bsb.rx_crc = bsb_crc_update(bsb.rx_crc, ch);
+                               if (bsb.rx_len < 4) {
+                                       // First three bytes: SOF, source addr, destination addr
+                               } else if (bsb.rx_len == 4) {
+                                       // Received length byte
+                                       if (bsb.rx_buf[BF_LEN] < 7 || bsb.rx_buf[BF_LEN] > BSB_MAX_SIZE) {
+                                               bsb_stats.rx_invalid++;
+                                               bsb.rx_len = 0;
+                                               BSB_DEBUG('L');
+                                       }
+                               } else if (bsb.rx_len == bsb.rx_buf[BF_LEN]) {
+                                       // Received a complete frame: check CRC and pass it to the main loop
+                                       if (bsb.rx_crc) {
+                                               bsb_stats.rx_bad_crc++;
+                                               BSB_DEBUG('C');
+                                       } else {
+                                               if (bsb_rx_frame_len) {
+                                                       // The previous one was not sent yet
+                                                       bsb_stats.rx_overruns++;
+                                                       BSB_DEBUG('O');
+                                               } else {
+                                                       bsb_rx_frame_len = bsb.rx_buf[BF_LEN];
+                                                       memcpy(bsb_rx_status_and_frame + 1, bsb.rx_buf, bsb_rx_frame_len);
+                                                       bsb_stats.rx_ok++;
+                                                       BSB_DEBUG('.');
+                                                       // Will match with expected replies in main loop
+                                               }
+                                               gpio_clear(GPIOB, GPIO1);
+                                               bsb.rx_led = 100;
+                                       }
+                                       bsb.rx_len = 0;
                                }
                        }
                }
        }
+
+       if (status & USART_SR_TXE) {
+               if (bsb.tx_state == TX_STATE_SENDING && bsb.tx_send_index < bsb.tx_len) {
+                       BSB_DEBUG('>');
+                       usart_send(USART3, bsb.tx_buf[bsb.tx_send_index++] ^ 0xff);
+               } else {
+                       usart_disable_tx_interrupt(USART3);
+                       // Main loop will be notified by receiving the echo of our frame,
+                       // so we do not need to wait for the "transmit complete" flag.
+               }
+       }
+}
+
+static void bsb_rx_step(void)
+{
+       cm_disable_interrupts();
+       barrier();
+       if (bsb.rx_len && ms_ticks - bsb.rx_timestamp >= BSB_RX_TIMEOUT) {
+               bsb.rx_len = 0;
+               bsb_stats.rx_timeouts++;
+               BSB_DEBUG('T');
+       }
+       if (bsb.rx_led) {
+               if (!--bsb.rx_led)
+                       gpio_set(GPIOB, GPIO1);
+       }
+       cm_enable_interrupts();
+}
+
+static void bsb_tx_step(void)
+{
+       switch (bsb.tx_state) {
+               case TX_STATE_WAITING_FOR_IDLE_LINE:
+                       if (ms_ticks - bsb.rx_timestamp < BSB_TX_IDLE_LINE)
+                               return;
+                       bsb.tx_state = TX_STATE_PRE_PACKET_DELAY;
+                       BSB_DEBUG('i');
+                       // Fall thru
+               case TX_STATE_PRE_PACKET_DELAY:
+                       if (ms_ticks - bsb.tx_start_timestamp > BSB_TX_TIMEOUT) {
+                               bsb.tx_state = TX_STATE_OFF;
+                               bsb_tx_result = TX_RESULT_TIMEOUT;
+                               bsb_stats.tx_timeouts++;
+                               return;
+                       }
+                       if (ms_ticks - bsb.rx_timestamp < BSB_TX_IDLE_LINE) {
+                               bsb.tx_state = TX_STATE_WAITING_FOR_IDLE_LINE;
+                               BSB_DEBUG('n');
+                               return;
+                       }
+                       if (--bsb.tx_ticks_to_send)
+                               return;
+                       BSB_DEBUG('s');
+                       bsb.rx_timestamp = ms_ticks;
+                       barrier();
+                       bsb.tx_state = TX_STATE_SENDING;
+                       barrier();
+                       usart_enable_tx_interrupt(USART3);
+                       return;
+               case TX_STATE_SENDING:
+                       // In this state, we can race with the USART interrupt handler
+                       cm_disable_interrupts();
+                       if (bsb.tx_state == TX_STATE_SENDING && ms_ticks - bsb.rx_timestamp >= BSB_RX_TIMEOUT) {
+                               // The echo of our packet was truncated due to collision
+                               bsb.tx_state = TX_STATE_COLLISION;
+                               BSB_DEBUG('t');
+                       }
+                       cm_enable_interrupts();
+                       return;
+               case TX_STATE_COLLISION:
+                       bsb_stats.tx_collisions++;
+                       bsb_attempt_tx();
+                       return;
+               case TX_STATE_SENT:
+                       if (!bsb.reply_type_mask) {
+                               // The frame needs no reply => confirm transmission
+                               bsb_stats.tx_ok_no_reply++;
+                               bsb.tx_state = TX_STATE_OFF;
+                               bsb_tx_result = TX_RESULT_OK;
+                       } else {
+                               bsb.tx_state = TX_STATE_WAITING_FOR_REPLY;
+                               bsb.tx_end_timestamp = ms_ticks;
+                               BSB_DEBUG('w');
+                       }
+                       return;
+               case TX_STATE_WAITING_FOR_REPLY:
+                       if (ms_ticks - bsb.tx_end_timestamp > BSB_REPLY_TIMEOUT) {
+                               // We did not receive a reply. Maybe the request was lost? Re-transmit it.
+                               bsb_stats.tx_reply_timeouts++;
+                               BSB_DEBUG('t');
+                               bsb_attempt_tx();
+                       }
+                       return;
+               default:
+                       ;
+       }
+}
+
+static void bsb_attempt_tx(void)
+{
+       if (bsb.tx_attempts++ >= BSB_TX_MAX_ATTEMPTS) {
+               bsb.tx_state = TX_STATE_OFF;
+               bsb_tx_result = TX_RESULT_TOO_MANY_RETRIES;
+               return;
+       }
+
+       bsb.tx_ticks_to_send = (random_u32() | 0x80000000) >> (32 - BSB_TX_WAIT_LOG - (bsb.tx_attempts-1));
+
+       bsb.tx_state = TX_STATE_WAITING_FOR_IDLE_LINE;
+       bsb.tx_send_index = 0;
+       bsb.tx_check_index = 0;
+       debug_printf("TX: Attempt #%u, wait for %u ms\n", bsb.tx_attempts, (uint) bsb.tx_ticks_to_send);
+}
+
+static void bsb_send(byte *buf, uint len)
+{
+       // If a transmit is in progress, declare overrrun
+       if (bsb_tx_result != TX_RESULT_NONE) {
+               bsb_stats.tx_overruns++;
+               return;
+       }
+       if (bsb.tx_state != TX_STATE_OFF) {
+               bsb_stats.tx_overruns++;
+               bsb_tx_result = TX_RESULT_OVERRUN;
+               return;
+       }
+
+       // Check frame validity
+       if (len < 7 || len > BSB_MAX_SIZE || buf[BF_SOF] != 0xdc || buf[BF_LEN] != len) {
+               bsb_stats.tx_rejects++;
+               bsb_tx_result = TX_RESULT_MALFORMED;
+               return;
+       }
+
+       // Detect frame type and prepare expected reply types
+       if (buf[BF_OP] == BSB_OP_QUERY) {
+               // So far, we allow only QUERY frames
+               bsb.reply_type_mask = (1 << BSB_OP_ANSWER) | (1 << BSB_OP_ERROR);
+       } else {
+               bsb_stats.tx_rejects++;
+               bsb_tx_result = TX_RESULT_FORBIDDEN;
+               return;
+       }
+
+       // Fill in source address
+       buf[BF_SRC] = 0x80 + BSB_ADDR_GATEWAY;
+
+       // Calculate CRC
+       u16 crc = 0;
+       for (uint i = 0; i < len - 2; i++)
+               crc = bsb_crc_update(crc, buf[i]);
+       buf[len-2] = crc >> 8;
+       buf[len-1] = crc;
+       debug_printf("TX: Prepared frame: type=%02x dest=%02x len=%u crc=%04x reply=%08x\n", buf[BF_OP], buf[BF_DEST], len, crc, (uint) bsb.reply_type_mask);
+
+       // Queue frame for transmission
+       memcpy(bsb.tx_buf, buf, len);
+       bsb.tx_len = len;
+       bsb.tx_start_timestamp = ms_ticks;
+       bsb.tx_attempts = 0;
+       bsb_attempt_tx();
+
+       // Light the TX LED
+       gpio_clear(GPIOB, GPIO0);
+}
+
+static void bsb_check_reply(void)
+{
+       // Match received frame in bsb_rx_status_and_frame to expected replies
+       // and set the status in byte 0.
+
+       byte *frame = bsb_rx_status_and_frame + 1;
+       // XXX: This might be executed too fast, so we can still be in TX_STATE_SENT
+       if (bsb.tx_state == TX_STATE_WAITING_FOR_REPLY || bsb.tx_state == TX_STATE_SENT) {
+               if (frame[BF_DEST] == BSB_ADDR_GATEWAY &&
+                   frame[BF_SRC] == bsb.tx_buf[BF_DEST] ^ 0x80 &&
+                   frame[BF_OP] < 32 &&
+                   bsb.reply_type_mask & (1 << frame[BF_OP])) {
+                       debug_printf("BSB: Matched reply\n");
+                       bsb.tx_state = TX_STATE_OFF;
+                       bsb_stats.tx_ok_replied++;
+                       bsb_rx_status_and_frame[0] = TX_RESULT_OK;
+                       gpio_set(GPIOB, GPIO0);         // Turn the TX LED off
+                       return;
+               }
+       }
+
+       bsb_rx_status_and_frame[0] = TX_RESULT_NONE;
 }
 
 static void bsb_init(void)
@@ -179,6 +471,20 @@ static void bsb_init(void)
 
 static usbd_device *usbd_dev;
 
+enum usb_string {
+       STR_MANUFACTURER = 1,
+       STR_PRODUCT,
+       STR_SERIAL,
+};
+
+static char usb_serial_number[13];
+
+static const char *usb_strings[] = {
+       "United Computer Wizards",
+       "BSB Gateway",
+       usb_serial_number,
+};
+
 static const struct usb_device_descriptor device = {
        .bLength = USB_DT_DEVICE_SIZE,
        .bDescriptorType = USB_DT_DEVICE,
@@ -187,23 +493,25 @@ static const struct usb_device_descriptor device = {
        .bDeviceSubClass = 0,
        .bDeviceProtocol = 0,
        .bMaxPacketSize0 = 64,
-       .idVendor = 0x4242,
-       .idProduct = 0x0003,
-       .bcdDevice = 0x0200,
-       .iManufacturer = 1,
-       .iProduct = 2,
-       .iSerialNumber = 3,
+       .idVendor = BSB_USB_VENDOR,
+       .idProduct = BSB_USB_PRODUCT,
+       .bcdDevice = BSB_USB_VERSION,
+       .iManufacturer = STR_MANUFACTURER,
+       .iProduct = STR_PRODUCT,
+       .iSerialNumber = STR_SERIAL,
        .bNumConfigurations = 1,
 };
 
 static const struct usb_endpoint_descriptor endpoints[] = {{
+       // Bulk end-point for sending frames to BSB
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,
-       .bEndpointAddress = 0x81,
+       .bEndpointAddress = 0x01,
        .bmAttributes = USB_ENDPOINT_ATTR_BULK,
        .wMaxPacketSize = 64,
        .bInterval = 1,
 },{
+       // Interrupt end-point for receiving frames from BSB
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,
        .bEndpointAddress = 0x82,
@@ -269,16 +577,8 @@ static const struct usb_config_descriptor config = {
        .interface = ifaces,
 };
 
-static char usb_serial_number[13];
-
-static const char *usb_strings[] = {
-       "United Computer Wizards",
-       "BSB Gateway",
-       usb_serial_number,
-};
-
 static byte usb_configured;
-static byte usb_rx_pending;
+static byte usb_ep82_pending;
 static uint8_t usbd_control_buffer[64];
 
 static enum usbd_request_return_codes control_cb(
@@ -292,9 +592,9 @@ static enum usbd_request_return_codes control_cb(
                return USBD_REQ_NOTSUPP;
 
        // We support reading of statistics via control requests
-       debug_printf("USB: Control request: Read statistics\n");
-       uint n = MIN(*len, sizeof(bsb_stat));
-       memcpy(*buf, (char *) &bsb_stat, n);
+       debug_printf("USB: Reading statistics\n");
+       uint n = MIN(*len, sizeof(bsb_stats));
+       memcpy(*buf, (char *) &bsb_stats, n);
        *len = n;
 
        return USBD_REQ_HANDLED;
@@ -321,34 +621,36 @@ static enum usbd_request_return_codes dfu_control_cb(usbd_device *dev UNUSED,
        return USBD_REQ_HANDLED;
 }
 
-static void ep81_cb(usbd_device *dev, uint8_t ep UNUSED)
+static void ep01_cb(usbd_device *dev, uint8_t ep UNUSED)
 {
-       byte buf[4];
-       put_u32_be(buf, ms_ticks);
-       usbd_ep_write_packet(dev, 0x81, buf, sizeof(buf));
-       debug_printf("USB: Bulk write\n");
+       // We received a frame from the USB host
+       byte buf[64];
+       uint len = usbd_ep_read_packet(dev, 0x01, buf, sizeof(buf));
+       debug_printf("USB: Host sent %u bytes\n", len);
+       bsb_send(buf, len);
 }
 
-static void rx_cb(usbd_device *dev UNUSED, uint8_t ep UNUSED)
+static void ep82_cb(usbd_device *dev UNUSED, uint8_t ep UNUSED)
 {
-       // Received packet passed through interrupt end-point
-       debug_printf("USB: RX EP done\n");
-       usb_rx_pending = 0;
+       // The frame was accepted by the USB host
+       debug_printf("USB: Interrupt done\n");
+       usb_ep82_pending = 0;
 }
 
 static void set_config_cb(usbd_device *dev, uint16_t wValue UNUSED)
 {
-       usbd_register_control_callback(dev,
+       usbd_register_control_callback(
+               dev,
                USB_REQ_TYPE_VENDOR,
                USB_REQ_TYPE_TYPE,
                control_cb);
-       usbd_register_control_callback(dev,
+       usbd_register_control_callback(
+               dev,
                USB_REQ_TYPE_CLASS | USB_REQ_TYPE_INTERFACE,
                USB_REQ_TYPE_TYPE | USB_REQ_TYPE_RECIPIENT,
                dfu_control_cb);
-       usbd_ep_setup(dev, 0x81, USB_ENDPOINT_ATTR_BULK, 64, ep81_cb);
-       usbd_ep_setup(dev, 0x82, USB_ENDPOINT_ATTR_BULK, 64, rx_cb);
-       ep81_cb(dev, 0);
+       usbd_ep_setup(dev, 0x01, USB_ENDPOINT_ATTR_BULK, 64, ep01_cb);
+       usbd_ep_setup(dev, 0x82, USB_ENDPOINT_ATTR_INTERRUPT, 64, ep82_cb);
        usb_configured = 1;
 }
 
@@ -356,6 +658,7 @@ static void reset_cb(void)
 {
        debug_printf("USB: Reset\n");
        usb_configured = 0;
+       usb_ep82_pending = 0;
 }
 
 static volatile bool usb_event_pending;
@@ -379,7 +682,7 @@ static void usb_init(void)
        // Simulate USB disconnect
        gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, GPIO11 | GPIO12);
        gpio_clear(GPIOA, GPIO11 | GPIO12);
-       delay_ms(1000);
+       delay_ms(100);
 
        usbd_dev = usbd_init(
                &st_usbfs_v1_usb_driver,
@@ -404,19 +707,20 @@ int main(void)
        tick_init();
        usart_init();
        desig_get_unique_id_as_dfu(usb_serial_number);
+       random_init();
 
-       debug_printf("Hello, kitty!\n");
+       debug_printf("Hail, Lord Damian! Thy BSB interface is ready.\n");
 
        bsb_init();
        usb_init();
 
-       u32 last_ds_step = 0;
+       u32 last_blink = 0;
+       u32 last_step = 0;
 
        for (;;) {
-               if (ms_ticks - last_ds_step >= 100) {
+               if (ms_ticks - last_blink >= 100) {
                        debug_led_toggle();
-                       gpio_toggle(GPIOB, GPIO0);
-                       last_ds_step = ms_ticks;
+                       last_blink = ms_ticks;
                }
 
                if (usb_event_pending) {
@@ -427,31 +731,33 @@ int main(void)
                }
 
                if (usb_configured) {
-                       // Passing of received packets to USB
-                       if (!usb_rx_pending) {
+                       // Passing of received frames to USB
+                       if (!usb_ep82_pending) {
                                if (bsb_rx_frame_len) {
+                                       // Received frame, possibly marked as reply
                                        barrier();
-                                       usbd_ep_write_packet(usbd_dev, 0x82, bsb_rx_frame, bsb_rx_frame_len);
-                                       usb_rx_pending = 1;
+                                       bsb_check_reply();
+                                       usbd_ep_write_packet(usbd_dev, 0x82, bsb_rx_status_and_frame, 1 + bsb_rx_frame_len);
+                                       usb_ep82_pending = 1;
                                        barrier();
                                        bsb_rx_frame_len = 0;
-                                       debug_printf("USB: RX started\n");
+                                       debug_printf("USB: Sending frame to interrupt EP\n");
+                               } else if (bsb_tx_result != TX_RESULT_NONE) {
+                                       // Only a transmission result
+                                       usbd_ep_write_packet(usbd_dev, 0x82, &bsb_tx_result, 1);
+                                       usb_ep82_pending = 1;
+                                       gpio_set(GPIOB, GPIO0);         // Turn the TX LED off
+                                       debug_printf("USB: Sending status %u to interrupt EP\n", bsb_tx_result);
+                                       bsb_tx_result = TX_RESULT_NONE;
                                }
                        }
                }
 
-               // Packet timeouts
-               cm_disable_interrupts();
-               barrier();
-               if (bsb_rx_len && (bsb_rx_timestamp - ms_ticks) >= BSB_RX_TIMEOUT) {
-                       bsb_rx_len = 0;
-                       bsb_stat.rx_timeouts++;
-               }
-               if (bsb_rx_frame_led) {
-                       if (!--bsb_rx_frame_led)
-                               gpio_set(GPIOB, GPIO1);
+               if (ms_ticks != last_step) {
+                       last_step = ms_ticks;
+                       bsb_rx_step();
+                       bsb_tx_step();
                }
-               cm_enable_interrupts();
 
                wait_for_interrupt();
        }