Delay in the physical world always came with time relay transmission and reflection. The sound to the edge of the space, the sound reflected listener’s ear, later than the direct sound. That cause delay. And this is the basic mechanism of all the time-related effects, such as echo, flange, Hass.

When me and my friend talking in the elevator, his voice bouncing between the smooth surface, and some of the reflection(early-reflection) flying into my ear with a little delay compare to his raw voice. Their combination will eliminate part of the energy on certain frequencies. Which makes his voice sound…

Solve the GPIO problem on Raspberry Pi 4B

I ran a UDA1334 on Raspberry Pi Zero before, and it worked great. But this week, when I connect the same chip on Raspberry Pi 4B, follow the same installing process, there was no sound came out.

Wiring of the I2S Decoder UDA1334A to the Raspberry Pi

Amp Vin to Raspberry Pi 3V or 5V
Amp GND to Raspberry Pi GND
Amp DIN to Raspberry Pi #21
Amp BCLK to Raspberry Pi #18
Amp LRCLK to Raspberry Pi #19

Setup I2S Decoder UDA1334A Driver on Raspberry Pi

Use this code to install the driver on raspberry pi.

curl -sS https://raw.githubusercontent.com/adafruit/Raspberry-Pi-Installer-Scripts/master/i2samp.sh | bash

After the auto reboot, run the script again.

Speaker Test

…

Install Mosquitto On Raspberry Pi

1. Before installing the MQTT broker, update the operating system first.

sudo apt update
sudo apt full-upgrade

2. The mosquitto MQTT broker is available as part of the Raspbain repository, installing it becomes simple.

sudo apt install mosquitto mosquitto-clients

3. Verify the MQTT broker is running on my Raspberry Pi

sudo systemctl status mosquitto

If the broker running successfully, it will show:

Testing the Mosquitto Installation on the Raspberry Pi

1. Start up a subscriber in the terminal. The subscriber is listening to MQTT broker that running on the Raspberry Pi.
2. Here, use the Mosquitto client for subscribers that we installed earlier to do this.
3. In this example, I connect…

（机器女声）

(Robotic female voice)

乘车必须佩戴口罩，平台建议乘客后排落座

Passengers must wear masks on the car, and the platform(DIDI) recommends that passengers sit in the back seat.

接到尾号7024的乘客，现在去上海纽约大学北二门，送该乘客

Picked up the passenger with the phone tail number 7024, now go to the North Second Gate of New York University Shanghai, Carrying the passenger.

200米绕环岛右转

200 meters around the roundabout and turn right.

前方路口，请注意停车让行

At the intersection ahead, please stop and give way.

绕环岛右转

Turn right around the roundabout.

前方路口，使出环岛路，然后马上右转

At the intersection ahead, take Huandao Road and turn right immediately.

右转

Turn right

900米后 红绿灯路口左转，进入松林路

After 900 meters, turn left at the traffic light…

I designed a box that can contain all the components inside it.

I update the BOM a little bit.

FRS Strip: Test Swipe on the surface.

FRS Circle x 3: Test the touch on the surface.

LED x 2: One for power indication and the other for the status.

Seeduino Xiao: A smaller and cheaper Arduino board.

3.5mm Audio Input Jack: Input extern signal to the board.

DRV2605L: the Motor driver

The really good news this week is the antenna of the Arduino 33 is back on board again!

It’s been a long time since this antenna has left the board. This causes the Arduino to only got under -80 dBm wifi signal even the board is placed right next to the router. I could not withstand this.

And I know use solid iron is not a good way to bring it back, because I tried that before. After some search on the internet, I realize the combination of the hot gun and solder paste will be a better choice.

What…

ERM

LRA

I design a flow chart using the temperature to control the heater on/off. The temperature coming from a DHT-22 sensor connecting to the internet through the MQTT protocol.

The Node-Red connect to the MQTT broker first, and then the temperature data will be formatted by a function node before logged into the mqtt.log file.