diff --git a/esphome/components/cse7766/sensor.py b/esphome/components/cse7766/sensor.py
index 3e136dae49..ca829cb274 100644
--- a/esphome/components/cse7766/sensor.py
+++ b/esphome/components/cse7766/sensor.py
@@ -59,3 +59,9 @@ async def to_code(config):
         conf = config[CONF_POWER]
         sens = await sensor.new_sensor(conf)
         cg.add(var.set_power_sensor(sens))
+
+
+def validate(config, item_config):
+    uart.validate_device(
+        "cse7766", config, item_config, baud_rate=4800, require_tx=False
+    )
diff --git a/esphome/components/dfplayer/__init__.py b/esphome/components/dfplayer/__init__.py
index d23e40000e..4c276db63f 100644
--- a/esphome/components/dfplayer/__init__.py
+++ b/esphome/components/dfplayer/__init__.py
@@ -78,6 +78,12 @@ async def to_code(config):
         await automation.build_automation(trigger, [], conf)
 
 
+def validate(config, item_config):
+    uart.validate_device(
+        "dfplayer", config, item_config, baud_rate=9600, require_rx=False
+    )
+
+
 @automation.register_action(
     "dfplayer.play_next",
     NextAction,
diff --git a/esphome/components/ethernet/__init__.py b/esphome/components/ethernet/__init__.py
index c6f81e5046..94c9ddd2e9 100644
--- a/esphome/components/ethernet/__init__.py
+++ b/esphome/components/ethernet/__init__.py
@@ -59,7 +59,7 @@ IPAddress = cg.global_ns.class_("IPAddress")
 ManualIP = ethernet_ns.struct("ManualIP")
 
 
-def validate(config):
+def _validate(config):
     if CONF_USE_ADDRESS not in config:
         if CONF_MANUAL_IP in config:
             use_address = str(config[CONF_MANUAL_IP][CONF_STATIC_IP])
@@ -90,7 +90,7 @@ CONFIG_SCHEMA = cv.All(
             ),
         }
     ).extend(cv.COMPONENT_SCHEMA),
-    validate,
+    _validate,
 )
 
 
diff --git a/esphome/components/fastled_clockless/light.py b/esphome/components/fastled_clockless/light.py
index 17f72427e4..cfc62e930b 100644
--- a/esphome/components/fastled_clockless/light.py
+++ b/esphome/components/fastled_clockless/light.py
@@ -34,7 +34,7 @@ CHIPSETS = [
 ]
 
 
-def validate(value):
+def _validate(value):
     if value[CONF_CHIPSET] == "NEOPIXEL" and CONF_RGB_ORDER in value:
         raise cv.Invalid("NEOPIXEL doesn't support RGB order")
     return value
@@ -47,7 +47,7 @@ CONFIG_SCHEMA = cv.All(
             cv.Required(CONF_PIN): pins.output_pin,
         }
     ),
-    validate,
+    _validate,
 )
 
 
diff --git a/esphome/components/gps/__init__.py b/esphome/components/gps/__init__.py
index e982bd4dfd..57ae11ea4f 100644
--- a/esphome/components/gps/__init__.py
+++ b/esphome/components/gps/__init__.py
@@ -89,3 +89,7 @@ async def to_code(config):
 
     # https://platformio.org/lib/show/1655/TinyGPSPlus
     cg.add_library("1655", "1.0.2")  # TinyGPSPlus, has name conflict
+
+
+def validate(config, item_config):
+    uart.validate_device("gps", config, item_config, require_tx=False)
diff --git a/esphome/components/hm3301/sensor.py b/esphome/components/hm3301/sensor.py
index 6d77841d20..34555fdcd6 100644
--- a/esphome/components/hm3301/sensor.py
+++ b/esphome/components/hm3301/sensor.py
@@ -29,7 +29,7 @@ AQI_CALCULATION_TYPE = {
 }
 
 
-def validate(config):
+def _validate(config):
     if CONF_AQI in config and CONF_PM_2_5 not in config:
         raise cv.Invalid("AQI sensor requires PM 2.5")
     if CONF_AQI in config and CONF_PM_10_0 not in config:
@@ -72,7 +72,7 @@ CONFIG_SCHEMA = cv.All(
     )
     .extend(cv.polling_component_schema("60s"))
     .extend(i2c.i2c_device_schema(0x40)),
-    validate,
+    _validate,
 )
 
 
diff --git a/esphome/components/neopixelbus/light.py b/esphome/components/neopixelbus/light.py
index f643b476e8..59d784a614 100644
--- a/esphome/components/neopixelbus/light.py
+++ b/esphome/components/neopixelbus/light.py
@@ -150,7 +150,7 @@ def format_method(config):
     raise NotImplementedError
 
 
-def validate(config):
+def _validate(config):
     if CONF_PIN in config:
         if CONF_CLOCK_PIN in config or CONF_DATA_PIN in config:
             raise cv.Invalid("Cannot specify both 'pin' and 'clock_pin'+'data_pin'")
@@ -176,7 +176,7 @@ CONFIG_SCHEMA = cv.All(
             cv.Required(CONF_NUM_LEDS): cv.positive_not_null_int,
         }
     ).extend(cv.COMPONENT_SCHEMA),
-    validate,
+    _validate,
     validate_method_pin,
 )
 
diff --git a/esphome/components/rc522_spi/__init__.py b/esphome/components/rc522_spi/__init__.py
index b21af1d07f..68b1e64145 100644
--- a/esphome/components/rc522_spi/__init__.py
+++ b/esphome/components/rc522_spi/__init__.py
@@ -24,3 +24,8 @@ async def to_code(config):
     var = cg.new_Pvariable(config[CONF_ID])
     await rc522.setup_rc522(var, config)
     await spi.register_spi_device(var, config)
+
+
+def validate(config, item_config):
+    # validate given SPI hub is suitable for rc522_spi, it needs both miso and mosi
+    spi.validate_device("rc522_spi", config, item_config, True, True)
diff --git a/esphome/components/rtttl/__init__.py b/esphome/components/rtttl/__init__.py
index 3441a63b9a..7f860fe3d7 100644
--- a/esphome/components/rtttl/__init__.py
+++ b/esphome/components/rtttl/__init__.py
@@ -1,8 +1,11 @@
+import logging
 import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome import automation
 from esphome.components.output import FloatOutput
-from esphome.const import CONF_ID, CONF_OUTPUT, CONF_TRIGGER_ID
+from esphome.const import CONF_ID, CONF_OUTPUT, CONF_PLATFORM, CONF_TRIGGER_ID
+
+_LOGGER = logging.getLogger(__name__)
 
 CODEOWNERS = ["@glmnet"]
 CONF_RTTTL = "rtttl"
@@ -33,6 +36,33 @@ CONFIG_SCHEMA = cv.Schema(
 ).extend(cv.COMPONENT_SCHEMA)
 
 
+def validate(config, item_config):
+    # Not adding this to FloatOutput as this is the only component which needs `update_frequency`
+
+    parent_config = config.get_config_by_id(item_config[CONF_OUTPUT])
+    platform = parent_config[CONF_PLATFORM]
+
+    PWM_GOOD = ["esp8266_pwm", "ledc"]
+    PWM_BAD = [
+        "ac_dimmer ",
+        "esp32_dac",
+        "slow_pwm",
+        "mcp4725",
+        "pca9685",
+        "tlc59208f",
+        "my9231",
+        "sm16716",
+    ]
+
+    if platform in PWM_BAD:
+        raise ValueError(f"Component rtttl cannot use {platform} as output component")
+
+    if platform not in PWM_GOOD:
+        _LOGGER.warning(
+            "Component rtttl is not known to work with the selected output type. Make sure this output supports custom frequency output method."
+        )
+
+
 async def to_code(config):
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
diff --git a/esphome/components/sim800l/__init__.py b/esphome/components/sim800l/__init__.py
index f9f6d71cd2..40c011a769 100644
--- a/esphome/components/sim800l/__init__.py
+++ b/esphome/components/sim800l/__init__.py
@@ -54,6 +54,10 @@ async def to_code(config):
         )
 
 
+def validate(config, item_config):
+    uart.validate_device("sim800l", config, item_config, baud_rate=9600)
+
+
 SIM800L_SEND_SMS_SCHEMA = cv.Schema(
     {
         cv.GenerateID(): cv.use_id(Sim800LComponent),
diff --git a/esphome/components/spi/__init__.py b/esphome/components/spi/__init__.py
index 00d21e619e..e6e073c4a4 100644
--- a/esphome/components/spi/__init__.py
+++ b/esphome/components/spi/__init__.py
@@ -67,3 +67,11 @@ async def register_spi_device(var, config):
     if CONF_CS_PIN in config:
         pin = await cg.gpio_pin_expression(config[CONF_CS_PIN])
         cg.add(var.set_cs_pin(pin))
+
+
+def validate_device(name, config, item_config, require_mosi, require_miso):
+    spi_config = config.get_config_by_id(item_config[CONF_SPI_ID])
+    if require_mosi and CONF_MISO_PIN not in spi_config:
+        raise ValueError(f"Component {name} requires parent spi to declare miso_pin")
+    if require_miso and CONF_MOSI_PIN not in spi_config:
+        raise ValueError(f"Component {name} requires parent spi to declare mosi_pin")
diff --git a/esphome/components/uart/__init__.py b/esphome/components/uart/__init__.py
index fb82fd9aee..aaed333e34 100644
--- a/esphome/components/uart/__init__.py
+++ b/esphome/components/uart/__init__.py
@@ -92,6 +92,42 @@ async def to_code(config):
     cg.add(var.set_parity(config[CONF_PARITY]))
 
 
+def validate_device(
+    name, config, item_config, baud_rate=None, require_tx=True, require_rx=True
+):
+    if not hasattr(config, "uart_devices"):
+        config.uart_devices = {}
+    devices = config.uart_devices
+
+    uart_config = config.get_config_by_id(item_config[CONF_UART_ID])
+
+    uart_id = uart_config[CONF_ID]
+    device = devices.setdefault(uart_id, {})
+
+    if require_tx:
+        if CONF_TX_PIN not in uart_config:
+            raise ValueError(f"Component {name} requires parent uart to declare tx_pin")
+        if CONF_TX_PIN in device:
+            raise ValueError(
+                f"Component {name} cannot use the same uart.{CONF_TX_PIN} as component {device[CONF_TX_PIN]} is already using it"
+            )
+        device[CONF_TX_PIN] = name
+
+    if require_rx:
+        if CONF_RX_PIN not in uart_config:
+            raise ValueError(f"Component {name} requires parent uart to declare rx_pin")
+        if CONF_RX_PIN in device:
+            raise ValueError(
+                f"Component {name} cannot use the same uart.{CONF_RX_PIN} as component {device[CONF_RX_PIN]} is already using it"
+            )
+        device[CONF_RX_PIN] = name
+
+    if baud_rate and uart_config[CONF_BAUD_RATE] != baud_rate:
+        raise ValueError(
+            f"Component {name} requires parent uart baud rate be {baud_rate}"
+        )
+
+
 # A schema to use for all UART devices, all UART integrations must extend this!
 UART_DEVICE_SCHEMA = cv.Schema(
     {
diff --git a/esphome/components/wifi/__init__.py b/esphome/components/wifi/__init__.py
index d2676bce36..c45e179bc4 100644
--- a/esphome/components/wifi/__init__.py
+++ b/esphome/components/wifi/__init__.py
@@ -137,7 +137,7 @@ WIFI_NETWORK_STA = WIFI_NETWORK_BASE.extend(
 )
 
 
-def validate(config):
+def _validate(config):
     if CONF_PASSWORD in config and CONF_SSID not in config:
         raise cv.Invalid("Cannot have WiFi password without SSID!")
 
@@ -207,7 +207,7 @@ CONFIG_SCHEMA = cv.All(
             ),
         }
     ),
-    validate,
+    _validate,
 )
 
 
diff --git a/esphome/config.py b/esphome/config.py
index a1fc07a21f..fcd2fac90f 100644
--- a/esphome/config.py
+++ b/esphome/config.py
@@ -63,6 +63,8 @@ class Config(OrderedDict):
         # The values will be the paths to all "domain", for example (['logger'], 'logger')
         # or (['sensor', 'ultrasonic'], 'sensor.ultrasonic')
         self.output_paths = []  # type: List[Tuple[ConfigPath, str]]
+        # A list of components ids with the config path
+        self.declare_ids = []  # type: List[Tuple[core.ID, ConfigPath]]
 
     def add_error(self, error):
         # type: (vol.Invalid) -> None
@@ -161,6 +163,12 @@ class Config(OrderedDict):
             part.append(item_index)
         return part
 
+    def get_config_by_id(self, id):
+        for declared_id, path in self.declare_ids:
+            if declared_id.id == str(id):
+                return self.get_nested_item(path[:-1])
+        return None
+
 
 def iter_ids(config, path=None):
     path = path or []
@@ -181,7 +189,7 @@ def do_id_pass(result):  # type: (Config) -> None
     from esphome.cpp_generator import MockObjClass
     from esphome.cpp_types import Component
 
-    declare_ids = []  # type: List[Tuple[core.ID, ConfigPath]]
+    declare_ids = result.declare_ids  # type: List[Tuple[core.ID, ConfigPath]]
     searching_ids = []  # type: List[Tuple[core.ID, ConfigPath]]
     for id, path in iter_ids(result):
         if id.is_declaration:
@@ -546,6 +554,19 @@ def validate_config(config, command_line_substitutions):
         # Only parse IDs if no validation error. Otherwise
         # user gets confusing messages
         do_id_pass(result)
+
+    # 7. Final validation
+    if not result.errors:
+        # Inter - components validation
+        for path, conf, comp in validate_queue:
+            if comp.config_schema is None:
+                continue
+            if callable(comp.validate):
+                try:
+                    comp.validate(result, result.get_nested_item(path))
+                except ValueError as err:
+                    result.add_str_error(err, path)
+
     return result
 
 
diff --git a/esphome/loader.py b/esphome/loader.py
index c418008453..d9d407d787 100644
--- a/esphome/loader.py
+++ b/esphome/loader.py
@@ -80,6 +80,10 @@ class ComponentManifest:
     def codeowners(self) -> List[str]:
         return getattr(self.module, "CODEOWNERS", [])
 
+    @property
+    def validate(self):
+        return getattr(self.module, "validate", None)
+
     @property
     def source_files(self) -> Dict[Path, SourceFile]:
         ret = {}
diff --git a/tests/test3.yaml b/tests/test3.yaml
index 8104c70fbf..0a01405516 100644
--- a/tests/test3.yaml
+++ b/tests/test3.yaml
@@ -1,6 +1,6 @@
 esphome:
-  name: $devicename
-  comment: $devicecomment
+  name: $device_name
+  comment: $device_comment
   platform: ESP8266
   board: d1_mini
   build_path: build/test3
@@ -13,8 +13,8 @@ esphome:
     - custom.h
 
 substitutions:
-  devicename: test3
-  devicecomment: test3 device
+  device_name: test3
+  device_comment: test3 device
   min_sub: '0.03'
   max_sub: '12.0%'
 
@@ -213,9 +213,33 @@ spi:
   miso_pin: GPIO14
 
 uart:
-  - tx_pin: GPIO1
+  - id: uart1
+    tx_pin: GPIO1
     rx_pin: GPIO3
     baud_rate: 115200
+  - id: uart2
+    tx_pin: GPIO4
+    rx_pin: GPIO5
+    baud_rate: 9600
+  - id: uart3
+    tx_pin: GPIO4
+    rx_pin: GPIO5
+    baud_rate: 4800
+  - id: uart4
+    tx_pin: GPIO4
+    rx_pin: GPIO5
+    baud_rate: 9600
+  - id: uart5
+    tx_pin: GPIO4
+    rx_pin: GPIO5
+    baud_rate: 9600
+  - id: uart6
+    tx_pin: GPIO4
+    rx_pin: GPIO5
+    baud_rate: 9600
+
+modbus:
+  uart_id: uart1
 
 ota:
   safe_mode: True
@@ -369,6 +393,7 @@ sensor:
     active_power_b:
       name: ADE7953 Active Power B
   - platform: pzem004t
+    uart_id: uart3
     voltage:
       name: 'PZEM00T Voltage'
     current:
@@ -408,6 +433,7 @@ sensor:
       name: 'AQI'
       calculation_type: 'AQI'
   - platform: pmsx003
+    uart_id: uart2
     type: PMSX003
     pm_1_0:
       name: 'PM 1.0 Concentration'
@@ -415,25 +441,8 @@ sensor:
       name: 'PM 2.5 Concentration'
     pm_10_0:
       name: 'PM 10.0 Concentration'
-  - platform: pmsx003
-    type: PMS5003T
-    pm_2_5:
-      name: 'PM 2.5 Concentration'
-    temperature:
-      name: 'PMS Temperature'
-    humidity:
-      name: 'PMS Humidity'
-  - platform: pmsx003
-    type: PMS5003ST
-    pm_2_5:
-      name: 'PM 2.5 Concentration'
-    temperature:
-      name: 'PMS Temperature'
-    humidity:
-      name: 'PMS Humidity'
-    formaldehyde:
-      name: 'PMS Formaldehyde Concentration'
   - platform: cse7766
+    uart_id: uart3
     voltage:
       name: 'CSE7766 Voltage'
     current:
@@ -443,7 +452,7 @@ sensor:
   - platform: ezo
     id: ph_ezo
     address: 99
-    unit_of_measurement: 'pH'  
+    unit_of_measurement: 'pH'
   - platform: tof10120
     name: "Distance sensor"
     update_interval: 5s
@@ -867,6 +876,7 @@ light:
     effects:
       - wled:
       - adalight:
+          uart_id: uart3
       - e131:
           universe: 1
   - platform: hbridge
@@ -888,6 +898,7 @@ ttp229_bsf:
   scl_pin: D1
 
 sim800l:
+  uart_id: uart4
   on_sms_received:
     - lambda: |-
         std::string str;
@@ -900,6 +911,7 @@ sim800l:
         recipient: '+1234'
 
 dfplayer:
+  uart_id: uart5
   on_finished_playback:
     then:
       if:
@@ -913,6 +925,7 @@ tm1651:
   dio_pin: D5
 
 rf_bridge:
+  uart_id: uart5
   on_code_received:
     - lambda: |-
         uint32_t test;
@@ -1006,3 +1019,4 @@ fingerprint_grow:
         event: esphome.${devicename}_fingerprint_grow_enrollment_failed
         data:
           finger_id: !lambda 'return finger_id;'
+  uart_id: uart6