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繼上期電子發燒友用戶分享的HZHY-AI300G的測評之后，本期我們又迎來了一位新用戶的測評。測評內容如下：

終于懷著激動的心情拿到了這塊專門為工業應用設計的RK3588智能盒。除了主機外，還附帶了兩根天線和一個電源。

我拿到的是4G+32G的版本。

在接下來的一個月中，我會深度評測這塊開發板，并用它完成一個完整的項目。項目分為以下幾個部分完成：

車窗智能防結冰；
后視鏡智能調整；
倒車雷達方案對比；
可視無線倒車雷達；
車窗自動關閉及防夾手功能；
自動駐車及自動取消功能。

車窗智能防結冰

要實現車窗智能防結冰，方法是對車內的溫度實時監控，當車內外溫差過大時啟動風扇讓空氣流通，降低溫差。

那么實現項目的本質就是，如何通過MCU 檢測到溫度變化，并實現與HZHY-AI300G智能盒的雙向通訊，不但可以把溫度上報給HZHY-AI300G智能盒，同時當HZHY-AI300G智能盒下發通風指令時，MCU也可以正確執行。

我搭了一個簡單的電路來進行測試。其中使用BMP280作為溫度傳感器進行數據測量，而用一個小LED作為執行器，用來代表同風扇。MCU使用的是ESP32-S3開發板，開發環境方便起見使用的是Circuitpython。

Circuitpython開發環境準備這一步我就直接跳過，因為和我們評測的HZHY-AI300G智能盒無關。

我們通過兩個MQTT Topic來進行通信。第一個Topic是test/topic，這個topic用來從mcu上報傳感器數據到HZHY-AI300G智能盒；另一個topic是test/cmd，用來讓HZHY-AI300G智能盒下發指令給MCU。

MCU的主要功能為，測量溫度并每秒鐘上報；如果接收到HZHY-AI300G智能盒下發的信息則按指令開關LED。具體代碼如下，注意要把MQTT broker的地址改為HZHY-AI300G智能盒的IP：

import time
import wifi
import socketpool
import ssl
import adafruit_minimqtt.adafruit_minimqtt as MQTT
import json
# Define callback methods which are called when events occur
def connect(client, userdata, flags, rc):
# This function will be called when the client is connected
# successfully to the broker.
print("Connected to MQTT Broker!")
print("Flags: {0}\\n RC: {1}".format(flags, rc))
def disconnect(client, userdata, rc):
# This method is called when the client disconnects
# from the broker.
print("Disconnected from MQTT Broker!")
def subscribe(client, userdata, topic, granted_qos):
# This method is called when the client subscribes to a new feed.
print("Subscribed to {0} with QOS level {1}".format(topic, granted_qos))
def unsubscribe(client, userdata, topic, pid):
# This method is called when the client unsubscribes from a feed.
print("Unsubscribed from {0} with PID {1}".format(topic, pid))
def publish(client, userdata, topic, pid):
# This method is called when the client publishes data to a feed.
print("Published to {0} with PID {1}".format(topic, pid))
def message(client, topic, message):
# This method is called when a topic the client is subscribed to
# has a new message.
print(f"New message on topic {topic}: {message}")
pool = socketpool.SocketPool(wifi.radio)
ssl_context = ssl.create_default_context()
# Set up a MiniMQTT Client
# NOTE: We'll need to connect insecurely for ethernet configurations.
mqtt_client = MQTT.MQTT(
broker="192.168.x.x",
port=1883,
username="",
password="",
is_ssl=False,
socket_pool=pool,
ssl_context=ssl_context,
# Connect callback handlers to client
mqtt_client.on_connect = connect
mqtt_client.on_disconnect = disconnect
mqtt_client.on_subscribe = subscribe
mqtt_client.on_unsubscribe = unsubscribe
mqtt_client.on_publish = publish
mqtt_client.on_message = message
def func():
pass
# MQTT Topic
# Use this topic if you'd like to connect to a standard MQTT broker
mqtt_topic = "test/topic"
print("Attempting to connect to %s" % mqtt_client.broker)
try:
mqtt_client.disconnect()
except:
pass
mqtt_client.connect()
# print("Subscribing to %s" % mqtt_topic)
# mqtt_client.subscribe(mqtt_topic)
# print("Publishing to %s" % mqtt_topic)
# mqtt_client.publish(mqtt_topic, "Hello Broker!")
# print("Unsubscribing from %s" % mqtt_topic)
# mqtt_client.unsubscribe(mqtt_topic)
# print("Disconnecting from %s" % mqtt_client.broker)
# mqtt_client.disconnect()
import board
import busio
i2c = busio.I2C(scl=board.GPIO7, sda=board.GPIO6)
assert i2c.try_lock()
print(i2c.scan())
i2c.unlock()
# 溫度測試
if 1:
import adafruit_bmp280
bmp280 = adafruit_bmp280.Adafruit_BMP280_I2C(i2c, address=0x76)
bmp280.sea_level_pressure = 1013.25
import digitalio
led = digitalio.DigitalInOut(board.GPIO15)
led.direction = digitalio.Direction.OUTPUT
led.value = True
mqtt_client.subscribe("test/cmd")
def func(client, topic, message):
led.value = int(message)
print(f"New message on topic {topic}: {message}")
mqtt_client.on_message = func
while True:
# Poll the message queue
mqtt_client.loop(timeout=1)
msg = {"Temperature": bmp280.temperature}
# Send a new message
mqtt_client.publish(mqtt_topic, json.dumps(msg))
print(msg)
time.sleep(1)

接線方式：
SCL: 7
SDA: 6
LED: 15

HZHY-AI300G智能盒的代碼我們可以基于上一篇MQTT測試代碼修改。兩邊信息傳遞使用的json文本，這是一種非常有效的指令及數據傳遞方式。代碼如下，如果檢測到上報的溫度大于31度，則會要求開啟LED，否則則熄滅LED。

from paho.mqtt import client as mqtt_client
import json
broker = '127.0.0.1'
port = 1883
topic = "test/topic"
client_id = "receiver"
# username = 'user'
# password = 'password'
def connect_mqtt():
def on_connect(client, userdata, flags, rc, properties):
if rc == 0:
print("Connected to MQTT Broker!")
else:
print("Failed to connect, return code %d\\n", rc)
# Set Connecting Client ID
client = mqtt_client.Client(client_id=client_id, callback_api_version=mqtt_client.CallbackAPIVersion.VERSION2)
# client.username_pw_set(username, password)
client.on_connect = on_connect
client.connect(broker, port)
return client
def subscribe(client: mqtt_client):
def on_message(client, userdata, msg):
print(f"Received `{msg.payload.decode()}` from `{msg.topic}` topic")
my_dict = json.loads(msg.payload.decode())
if 'Temperature' in my_dict:
temp = int(my_dict["Temperature"])
if temp > 31:
client.publish("test/cmd", "0")
print("Too Hot!!!")
else:
client.publish("test/cmd", "1")
client.subscribe(topic)
client.on_message = on_message
def run():
client = connect_mqtt()
subscribe(client)
client.loop_forever()
if __name__ == '__main__':

run()

同時運行兩邊的代碼，可以看到智能盒打印出了收到的溫度信息，當溫度高于31度時，打印對應文本，并點亮MCU上的LED。

后視鏡智能調整

接下來我們來看一下執行器的控制。譬如后視鏡調整，警報驅動，窗機啟停等功能，實際上都是HZHY-AI300G智能盒向MCU下發指令控制執行器的過程。

我們使用一個舵機作為執行器，依然先完成MCU部分的增量代碼。代碼內容非常簡單，把接收到的舵機角度直接傳遞給舵機即可。

# 舵機測試
if 1:
import pwmio
from adafruit_motor import servo
pwm = pwmio.PWMOut(board.GPIO14, frequency=50)
s1 = servo.Servo(pwm, min_pulse=500, max_pulse=2500)
mqtt_client.subscribe("test/cmd")
def func(client, topic, message):
print(f"New message on topic {topic}: {message}")
s1.angle = int(message)
msg = {"angle": int(message)}
mqtt_client.publish(mqtt_topic, json.dumps(msg))
mqtt_client.on_message = func
while True:
# Poll the message queue
mqtt_client.loop(timeout=1)

舵機記得要使用5V供電，接在14號引腳上。

HZHY-AI300G智能盒由于是單純的下發指令，因此這次代碼我們可以基于一開始的發送代碼進行修改。出于測試目的，我們讓HZHY-AI300G智能盒下發每間隔1S旋轉舵機180度的指令：

import time
from paho.mqtt import client as mqtt_client
broker = '127.0.0.1'
port = 1883
topic = "test/topic"
client_id = "sender"
# username = 'user'
# password = 'password'
def connect_mqtt():
def on_connect(client, userdata, flags, rc, properties):
if rc == 0:
print("Connected to MQTT Broker!")
else:
print("Failed to connect, return code %d\\n", rc)
# Set Connecting Client ID
client = mqtt_client.Client(client_id=client_id, callback_api_version=mqtt_client.CallbackAPIVersion.VERSION2)
# client.username_pw_set(username, password)
client.on_connect = on_connect
client.connect(broker, port)
return client
def publish(client):
msg_count = 0
while True:
time.sleep(1)
msg = f"messages: {msg_count}"
result = client.publish(topic, msg)
# result: [0, 1]
status = result[0]
if status == 0:
print(f"Send `{msg}` to topic `{topic}`")
else:
print(f"Failed to send message to topic {topic}")
msg_count += 1
def run():
client = connect_mqtt()
# client.loop_start()
# publish(client)
# client.loop_stop()
# 舵機測試

if 1:
while True:
client.publish("test/cmd", "0")
time.sleep(1)
client.publish("test/cmd", "180")
time.sleep(1)
if __name__ == '__main__':

run()

兩邊代碼同時運行，我們就可以觀察到舵機按照要求運動起來。觀察MCU的控制臺輸出，可以看到打印出了接收到的數據信息：

而如果我們同步運行HZHY-AI300G智能盒上的接收代碼，也可以看到對應的反饋信息：

倒車雷達方案對比

倒車雷達兩種方案的驗證，同樣也是使用MCU獲取兩個傳感器得到的信號，并把數據一起上報給HZHY-AI300G智能盒。

MCU的代碼可以基于之前的代碼上做增量修改，因為MQTT通訊部份都是一樣的。增加如下部分就可以實現讀取兩個距離傳感器的數據，并上報給HZHY-AI300G智能盒：

# 測距測試

if 0:
import adafruit_vl53l0x
vl53 = adafruit_vl53l0x.VL53L0X(i2c)
import adafruit_us100
# Connect TX to TX, RX to RX
uart = busio.UART(board.GPIO4, board.GPIO5, baudrate=9600)
sonar = adafruit_us100.US100(uart)
while True:
# Poll the message queue
mqtt_client.loop(timeout=1)
msg = {"vl53l0x": vl53.range, "sonar": int(sonar.distance * 10)}
# Send a new message
mqtt_client.publish(mqtt_topic, json.dumps(msg))
print(msg)
time.sleep(1)