diff --git a/hw/avr/arduino.c b/hw/avr/arduino.c
index 3c8388490d..3ff31492fa 100644
--- a/hw/avr/arduino.c
+++ b/hw/avr/arduino.c
@@ -75,7 +75,10 @@ static void arduino_duemilanove_class_init(ObjectClass *oc, void *data)
     MachineClass *mc = MACHINE_CLASS(oc);
     ArduinoMachineClass *amc = ARDUINO_MACHINE_CLASS(oc);
 
-    /* https://www.arduino.cc/en/Main/ArduinoBoardDuemilanove */
+    /*
+     * https://www.arduino.cc/en/Main/ArduinoBoardDuemilanove
+     * https://www.arduino.cc/en/uploads/Main/arduino-duemilanove-schematic.pdf
+     */
     mc->desc        = "Arduino Duemilanove (ATmega168)",
     mc->alias       = "2009";
     amc->mcu_type   = TYPE_ATMEGA168_MCU;
@@ -87,7 +90,10 @@ static void arduino_uno_class_init(ObjectClass *oc, void *data)
     MachineClass *mc = MACHINE_CLASS(oc);
     ArduinoMachineClass *amc = ARDUINO_MACHINE_CLASS(oc);
 
-    /* https://store.arduino.cc/arduino-uno-rev3 */
+    /*
+     * https://store.arduino.cc/arduino-uno-rev3
+     * https://www.arduino.cc/en/uploads/Main/arduino-uno-schematic.pdf
+     */
     mc->desc        = "Arduino UNO (ATmega328P)";
     mc->alias       = "uno";
     amc->mcu_type   = TYPE_ATMEGA328_MCU;
@@ -99,7 +105,10 @@ static void arduino_mega_class_init(ObjectClass *oc, void *data)
     MachineClass *mc = MACHINE_CLASS(oc);
     ArduinoMachineClass *amc = ARDUINO_MACHINE_CLASS(oc);
 
-    /* https://www.arduino.cc/en/Main/ArduinoBoardMega */
+    /*
+     * https://www.arduino.cc/en/Main/ArduinoBoardMega
+     * https://www.arduino.cc/en/uploads/Main/arduino-mega2560-schematic.pdf
+     */
     mc->desc        = "Arduino Mega (ATmega1280)";
     mc->alias       = "mega";
     amc->mcu_type   = TYPE_ATMEGA1280_MCU;
@@ -111,7 +120,10 @@ static void arduino_mega2560_class_init(ObjectClass *oc, void *data)
     MachineClass *mc = MACHINE_CLASS(oc);
     ArduinoMachineClass *amc = ARDUINO_MACHINE_CLASS(oc);
 
-    /* https://store.arduino.cc/arduino-mega-2560-rev3 */
+    /*
+     * https://store.arduino.cc/arduino-mega-2560-rev3
+     * https://www.arduino.cc/en/uploads/Main/arduino-mega2560_R3-sch.pdf
+     */
     mc->desc        = "Arduino Mega 2560 (ATmega2560)";
     mc->alias       = "mega2560";
     amc->mcu_type   = TYPE_ATMEGA2560_MCU;
diff --git a/hw/misc/led.c b/hw/misc/led.c
index 5266d026d0..f552b8b648 100644
--- a/hw/misc/led.c
+++ b/hw/misc/led.c
@@ -20,6 +20,7 @@ static const char * const led_color_name[] = {
     [LED_COLOR_BLUE]    = "blue",
     [LED_COLOR_CYAN]    = "cyan",
     [LED_COLOR_GREEN]   = "green",
+    [LED_COLOR_YELLOW]  = "yellow",
     [LED_COLOR_AMBER]   = "amber",
     [LED_COLOR_ORANGE]  = "orange",
     [LED_COLOR_RED]     = "red",
diff --git a/include/hw/misc/led.h b/include/hw/misc/led.h
index aa359b87c2..29c0879570 100644
--- a/include/hw/misc/led.h
+++ b/include/hw/misc/led.h
@@ -27,6 +27,7 @@ typedef enum {          /* Coarse wavelength range */
     LED_COLOR_BLUE,     /* 475 nm */
     LED_COLOR_CYAN,     /* 500 nm */
     LED_COLOR_GREEN,    /* 535 nm */
+    LED_COLOR_YELLOW,   /* 567 nm */
     LED_COLOR_AMBER,    /* 590 nm */
     LED_COLOR_ORANGE,   /* 615 nm */
     LED_COLOR_RED,      /* 630 nm */
diff --git a/target/avr/helper.c b/target/avr/helper.c
index 65880b9928..35e1019594 100644
--- a/target/avr/helper.c
+++ b/target/avr/helper.c
@@ -49,7 +49,9 @@ bool avr_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
             cc->tcg_ops->do_interrupt(cs);
 
             env->intsrc &= env->intsrc - 1; /* clear the interrupt */
-            cs->interrupt_request &= ~CPU_INTERRUPT_HARD;
+            if (!env->intsrc) {
+                cs->interrupt_request &= ~CPU_INTERRUPT_HARD;
+            }
 
             ret = true;
         }
@@ -98,7 +100,7 @@ int avr_cpu_memory_rw_debug(CPUState *cs, vaddr addr, uint8_t *buf,
 
 hwaddr avr_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
 {
-    return addr; /* I assume 1:1 address correspondance */
+    return addr; /* I assume 1:1 address correspondence */
 }
 
 bool avr_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
@@ -299,7 +301,7 @@ void helper_outb(CPUAVRState *env, uint32_t port, uint32_t data)
 }
 
 /*
- *  this function implements LD instruction when there is a posibility to read
+ *  this function implements LD instruction when there is a possibility to read
  *  from a CPU register
  */
 target_ulong helper_fullrd(CPUAVRState *env, uint32_t addr)
@@ -323,7 +325,7 @@ target_ulong helper_fullrd(CPUAVRState *env, uint32_t addr)
 }
 
 /*
- *  this function implements ST instruction when there is a posibility to write
+ *  this function implements ST instruction when there is a possibility to write
  *  into a CPU register
  */
 void helper_fullwr(CPUAVRState *env, uint32_t data, uint32_t addr)