Test device: suspend and resume

test-devices/loopback-stm32/.vscode/settings.json

@@ -3,6 +3,9 @@
         "usbd.h": "c",
         "usbd_pvt.h": "c",
         "dwc2_stm32.h": "c",
-        "stm32f7xx.h": "c"
+        "stm32f7xx.h": "c",
+        "stm32f4xx.h": "c",
+        "stm32f401xc.h": "c",
+        "stm32f401xe.h": "c"
     }
 }

test-devices/loopback-stm32/src/board.h

@@ -28,6 +28,9 @@ void board_led_write(bool on);
 // Return the number of milliseconds since a time in the past
 uint32_t board_millis(void);
 
+// Enter sleep or stop mode and wake up on USB resume
+void board_sleep(void);
+
 // USB serial number
 extern char board_serial_num[13];
 

test-devices/loopback-stm32/src/board_f1.c

@@ -15,6 +15,8 @@
 #include "stm32f1xx.h"
 #include "device/usbd.h"
 
+#define EXTI_USBWakeUp_Line EXTI_IMR_IM18
+
 
 extern uint32_t SystemCoreClock;
 void SystemCoreClockUpdate(void);
@@ -180,6 +182,12 @@ void board_init(void) {
     gpio_set_mode(GPIOB, 12, GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_PUSH_PULL);
 
 	usb_init_serial_num();
+
+	// Wake up event is only available as interrupt, not as an event.
+	// See product errata sheet
+	set_reg(&EXTI->RTSR, EXTI_USBWakeUp_Line, EXTI_USBWakeUp_Line);
+	set_reg(&EXTI->IMR, EXTI_USBWakeUp_Line, EXTI_USBWakeUp_Line);
+	NVIC_EnableIRQ(USBWakeUp_IRQn);
 }
 
 uint32_t board_millis(void) {
@@ -188,9 +196,38 @@ uint32_t board_millis(void) {
 
 void board_led_write(bool on) {
     if (on)
-        gpio_set(GPIOB, 12);
-    else
         gpio_clear(GPIOB, 12);
+    else
+        gpio_set(GPIOB, 12);
+}
+
+void board_sleep(void) {
+
+	// turn off LED
+	board_led_write(false);
+
+	// pause systick interrupts
+	set_reg(&SysTick->CTRL, 0, SysTick_CTRL_TICKINT_Msk);
+
+	// enter Stop mode when the CPU enters deep sleep
+	set_reg(&PWR->CR, 0, PWR_CR_PDDS_Msk | PWR_CR_LPDS_Msk);
+
+	set_reg(&SCB->SCR, SCB_SCR_SLEEPDEEP_Msk, SCB_SCR_SLEEPDEEP_Msk);
+
+	// sleep until an interrupt occurs
+	__WFI();
+
+	// reset SLEEPDEEP bit
+	set_reg(&SCB->SCR, 0, SCB_SCR_SLEEPDEEP_Msk);
+
+	// after wakeup, re-enable PLL as clock source
+    rcc_clock_setup_in_hse_8mhz_out_72mhz();
+
+	// resume systick interrupts
+	set_reg(&SysTick->CTRL, SysTick_CTRL_TICKINT_Msk, SysTick_CTRL_TICKINT_Msk);
+
+	// turn on LED
+	board_led_write(true);
 }
 
 
@@ -201,7 +238,8 @@ void SysTick_Handler (void) {
 }
 
 void USBWakeUp_IRQHandler(void) {
-    tud_int_handler(0);
+	// clear interrupt
+	EXTI->PR = EXTI_USBWakeUp_Line;
 }
 
 void USB_HP_IRQHandler(void) {

test-devices/loopback-stm32/src/board_f4.c

@@ -15,6 +15,9 @@
 #include "stm32f4xx.h"
 #include "device/usbd.h"
 
+#define EXTI_USBWakeUp_Line EXTI_IMR_IM18
+
+
 extern uint32_t SystemCoreClock;
 void SystemCoreClockUpdate(void);
 
@@ -59,7 +62,7 @@ const rcc_clock_setup_t clock_setup_hse_value_out_84mhz_3v3 = {
 	.hpre = RCC_CFGR_HPRE_DIV1,
 	.ppre1 = RCC_CFGR_PPRE1_DIV2,
 	.ppre2 = RCC_CFGR_PPRE2_DIV1,
-	.voltage_scale = PWR_CR_VOS_SCALE1,
+	.voltage_scale = PWR_CR_VOS_SCALE2,
 	.flash_config = FLASH_ACR_DCEN | FLASH_ACR_ICEN | FLASH_ACR_LATENCY_2WS
 };
 
@@ -85,6 +88,11 @@ const rcc_clock_setup_t clock_setup_hse_value_out_84mhz_3v3 = {
 #define GPIO_OSPEED_HIGH 3
 
 
+// --- additional USB register
+#define PCGCCTL ((volatile uint32_t *)((uint32_t)USB_OTG_FS + USB_OTG_PCGCCTL_BASE))
+
+
+
 static inline void rcc_wait_for_osc_ready(uint32_t rcc_cr_clk_rdy) {
 	while (get_reg(&RCC->CR, rcc_cr_clk_rdy) == 0)
 		;
@@ -254,6 +262,13 @@ void board_init(void) {
 	gpio_mode_setup(GPIOC, 13, GPIO_MODE_OUTPUT, GPIO_PUPD_NO_PULL);
 
 	usb_init_serial_num();
+
+	// enable USB wakeup interrupt
+	EXTI->PR = EXTI_USBWakeUp_Line;
+	EXTI->RTSR |= EXTI_USBWakeUp_Line;
+	EXTI->IMR |= EXTI_USBWakeUp_Line;
+    NVIC_SetPriority(OTG_FS_WKUP_IRQn, 0);
+	NVIC_EnableIRQ(OTG_FS_WKUP_IRQn);
 }
 
 uint32_t board_millis(void) {
@@ -262,9 +277,44 @@ uint32_t board_millis(void) {
 
 void board_led_write(bool on) {
     if (on)
-        gpio_set(GPIOC, 13);
-    else
         gpio_clear(GPIOC, 13);
+    else
+        gpio_set(GPIOC, 13);
+}
+
+void board_sleep(void) {
+
+	// turn off LED
+	board_led_write(false);
+
+	// stop PCLK to USB
+	set_reg(PCGCCTL, USB_OTG_PCGCCTL_STOPCLK, USB_OTG_PCGCCTL_STOPCLK_Msk);
+
+	// pause systick interrupts
+	set_reg(&SysTick->CTRL, 0, SysTick_CTRL_TICKINT_Msk);
+
+	// enter stop mode when the CPU enters deep sleep
+	set_reg(&PWR->CR, 0, PWR_CR_PDDS_Msk | PWR_CR_LPDS_Msk);
+
+	// use deep sleep mode
+	set_reg(&SCB->SCR, SCB_SCR_SLEEPDEEP_Msk, SCB_SCR_SLEEPDEEP_Msk);
+
+    __WFI();
+
+	// reset to regular sleep mode
+	set_reg(&SCB->SCR, 0, SCB_SCR_SLEEPDEEP_Msk);
+
+	// after wakeup, re-enable PLL as clock source
+	rcc_clock_setup_pll(&clock_setup_hse_value_out_84mhz_3v3);
+
+	// resume systick interrupts
+	set_reg(&SysTick->CTRL, SysTick_CTRL_TICKINT_Msk, SysTick_CTRL_TICKINT_Msk);
+
+	// restart PCLK to USB
+	set_reg(PCGCCTL, 0, USB_OTG_PCGCCTL_STOPCLK_Msk);
+
+	// turn on LED
+	board_led_write(true);
 }
 
 
@@ -278,4 +328,9 @@ void OTG_FS_IRQHandler(void) {
     tud_int_handler(0);
 }
 
+void OTG_FS_WKUP_IRQHandler(void) {
+	// clear interrupt
+	EXTI->PR = EXTI_USBWakeUp_Line;
+}
+
 #endif

test-devices/loopback-stm32/src/board_f7.c

@@ -284,6 +284,10 @@ void board_init(void) {
 	usb_init_serial_num();
 }
 
+void board_sleep(void) {
+	// not implemented yet
+}
+
 uint32_t board_millis(void) {
     return millis_count;
 }

test-devices/loopback-stm32/src/main.c

@@ -42,7 +42,6 @@ int num_echos;
 enum  {
     BLINK_NOT_MOUNTED = 250,
     BLINK_MOUNTED = 1000,
-    BLINK_SUSPENDED = 2500,
 };
 
 static uint32_t blink_interval_ms = BLINK_NOT_MOUNTED;
@@ -288,12 +287,7 @@ void tud_umount_cb(void) {
 // Within 7ms, device must draw an average of current less than 2.5 mA from bus
 void tud_suspend_cb(bool remote_wakeup_en) {
     (void) remote_wakeup_en;
-    blink_interval_ms = BLINK_SUSPENDED;
-}
-
-// Invoked when usb bus is resumed
-void tud_resume_cb(void) {
-    blink_interval_ms = BLINK_MOUNTED;
+    board_sleep();
 }
 
 
@@ -305,7 +299,7 @@ void led_blinking_task(void) {
 
     // Blink every interval ms
     if ( board_millis() - start_ms < blink_interval_ms)
-        return; // not enough time
+        return; // interval not elapsed yet
     start_ms += blink_interval_ms;
 
     board_led_write(led_state);

test-devices/loopback-stm32/src/usb_descriptors.c

@@ -57,7 +57,7 @@ enum {
 
 uint8_t const desc_fs_configuration[] = {
     // Config number, interface count, string index, total length, attribute, power in mA
-    TUD_CONFIG_DESCRIPTOR(1, INTF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, 0x00, 500),
+    TUD_CONFIG_DESCRIPTOR(1, INTF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, 0x80, 500),
     // Loopback interface (alternate 0)
     CUSTOM_VENDOR_INTERFACE(0, 4),
     // Loopback endpoint OUT